Tuna Zucchini Casserole

Someone was once trying out for a job at a restaurant I worked at, who cooked a meal that had a course which paired fish with cheese. I don’t recall if he got the job or not, but I do remember someone in the kitchen muttering, “Everyone knows that fish and cheese don’t go together.” I don’t know who gave him that information, but everyone who has ever had a tuna melt knows that, indeed – yes – they do.

I’m not sure where the tuna melt came from, but it was always a favorite sandwich of mine. Sharp cheddar melted over a thick layer of tuna salad, spread on a piece of bread. I think we even made those in the GE toast oven when I was growing up, the one with a picture window and the two long black bars at the bottom, the longer one popping the oven door open with that familiar ker-clunk.

There’s also Tuna Noodle Casserole, which pairs the two seemingly incongruous ingredients, melded them in a baking dish, along with starchy noodles and a crunchy breaded topping.

I haven’t had one of those in years either, but when I got the book Six Seasons, and saw this recipe, I remembered how much I liked that combination, and hauled out my gratin dish, and picked up a couple of tins of tuna.

I love vegetables but am not especially creative with them and I often find vegetable cookbooks not super inspiring. I get them with high hopes about using them. But in the end, they languish on my shelf, testaments to unfulfilled aspirations. And I end up doing what I normally do; roast the vegetables in the oven with a little olive oil and salt, perhaps with a few branches of thyme or another herb.

Six Seasons, which is subtitled “A New Way with Vegetables,” really means it. It’s full of terrific ideas by Joshua McFadden that sprung out of the pages at me, with a similarly inviting kerclunk. If you’ve ever wondered what to make with those funny looking rounds of kohlrabi at the market, or what to do with that half-head of celery you’ve got leftover from making stock, there’s a recipe for Celery, Sausage, Provolone, Olives, and Pickled Peppers, that he calls a “salad like an Italian hoagie, but without the roll.” The Braised Celery and Radicchio Salad with Perfect Roast Chicken also sounds worth trying, too. In fact, I may pick up a head at the market this morning, just to make that this weekend.

Similarly, this Tuna Zucchini Casserole recipe is meant to mimic Tuna Noodle Casserole, but without the carb-load of pasta, replacing it with healthier vegetables. And who doesn’t want to include more vegetables in their diet?

Admittedly, zucchini may not be in season where you are at the moment. If not, don’t worry. You could make this with roasted or braised broccoli, fennel, or rutabagas and parsnips. Another idea would be to braise some greens, like kale, Swiss chard, mustard greens, or collards, with some garlic (and perhaps a bit of bacon?), and bake the tuna and cheese on a bed of that.

This is closer to a gratin than a casserole. And when I pulled it out of the oven, I started digging into the crusty bits around the edges, where the cheese fused together between the baking dish and the zucchini, creating caramelized bits of vegetable sweetness. The cheese on top bubbled and had that familiar chewy texture. Next time I get the craving for tuna and melted cheese, which I think is going to be more frequently now that I’ve had a nostalgic taste of it, I’m going to pull out this recipe and make it again.

Tuna Zucchini Casserole
Print Recipe
4 servings
Adapted from Six Seasons by Joshua McFaddenThis is a warming casserole that can be made in advance, and baked right before serving. Simply do all the steps through step 4 and refrigerate it, until ready to bake. It's best to let it come to room temperature before you do, so it heats evenly.It's perfect for lunch or dinner, along with a big green salad, and a glass of white wine.
1 1/2 pounds (680g) small zucchini or summer squash
2 1/2 teaspoons Kosher or sea salt
1 tablespoon extra-virgin olive oil, plus additional oil for preparing the zucchini
2 cups (200g) thinly sliced scallions or spring onions
1 1/2 teaspoons minced fresh thyme leaves
freshly ground black pepper
1/4 teaspoon red chili flakes
2 tins tuna, preferably packed in oil, light or dark (5 oz, 140g. each tin)
1 1/2 cups (130g) grated cheese, such as Comté, Gruyère, Emmenthal, extra-sharp cheddar, or Swiss cheese
1. Trim the ends off the zucchini and if small, slice them lengthwise. If they are larger, cut them into batons about 3/4 inch (2cm) thick. Place them in a colander and toss them with 2 teaspoons of salt. Let drain for 1 to 2 hours, shaking and turning them a few times, coaxing the excess water to drain away.
2. Heat the olive oil in a skillet over medium heat. Add the scallions, thyme, some freshly ground pepper, the chili flakes, and 1/2 teaspoon salt. Cook, stirring frequently, until the scallions are wilted and soft, about 3 minutes. Remove from heat and set aside.
3. Preheat the oven to 450ºF (230ºC). Blot the zucchini dry with a paper towel and toss them with a bit of olive oil on a baking sheet. (You can line the baking sheet with parchment paper for easier clean up if you want, or if you're parsimonious with the olive oil and are concerned they'll stick.) Spread them in an even layer, cut side down, and roast them in the oven just until tender, about 15 minutes, but don't cook them to mush.
4. Remove from the oven and place the zucchini in a single layer in a shallow baking dish or gratin dish that will fit them snugly in an even layer. Strew the scallions over the zucchini. Drain the tuna and flake it over the scallions and sprinkle the cheese evenly over the top.
5. Bake until the cheese is melted and starts to brown and the casserole is heated through, 10 to 15 minutes. Serve warm.


A warming casserole that melds roasted squash, tuna and melted cheese - comfort food at its best!

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50 comments

  • November 30, 2018 11:00am

    This looks yummy. I bet you could use spaghetti squash instead of noodles, too. The size of the zucchini looks ideal for not becoming mush with further cooking.

    Question: how does Romain like such dishes? My husband can’t stand having everything in one dish–he says the French way is to have vegetables, féculants and meat/fish all separate. Reply

    • November 30, 2018 11:11am
      David Lebovitz

      He’s very open about eating everything, although we do have friends that insist on things in courses, or separate; meat, grains, vegetables, etc..

      He also prefers his coffee with dessert, and was recently telling some friends that they should try Mexican food…because it was so good (!) Reply

  • November 30, 2018 3:39pm

    I LOVE this! I thought I was the only person who liked tuna casserole and especially one with cheese. Can’t wait to try this version. Reply

  • November 30, 2018 3:48pm

    Sounds delicious, except that I can’t eat onions. And TWO CUPS is a lot. What suggestions do you have for a substitute for the onions-or does that just change the dish so much I shouldn’t even try. Reply

    • November 30, 2018 3:52pm
      David Lebovitz

      It might sound like a lot, but they cook down considerably. (I actually used a little less than the original recipe called for.) In place of the scallions, you could saute some chopped arugula, or perhaps some radicchio, in its place. Reply

  • Alyson
    November 30, 2018 3:54pm

    What a great way to deal with fridge oddments! A soft goats cheese would be a tasty topping too.. Reply

  • Judith Cheney
    November 30, 2018 3:56pm

    I am going to make this next week for my son who comes over to handy-man for me, his poor old mither, & I make supper for us & we have a nice visit. He will love it, as he does any seafood, or casserole dish. Hooray! and merci beaucoup. Reply

  • Liz Garvin
    November 30, 2018 3:57pm

    Perhaps I could make zucchini noodles ? Reply

    • GingerF
      November 30, 2018 4:10pm

      I was thinking the same thing! Reply

      • Amy
        December 1, 2018 3:53pm

        Same here! Reply

  • Tara Roberts
    November 30, 2018 4:15pm

    I love Six Seasons! As soon as I saw the picture, I thought that was where you got the inspiration. You really need to try the roasted carrot and farro recipe. You serve it on top of the whipped ricotta (which I could eat with a spoon) and I think is my favorite recipe in the whole book. Reply

  • November 30, 2018 4:28pm

    I will try this at work! My co-worker is gluten intolerant, so no worries about noodles or bread! Reply

  • Cris S.
    November 30, 2018 4:33pm

    Last time we were in Paris (sadly, more than five years ago now) we went to an up and coming restaurant recommended here and other places. It was lovely, small menu, and so my husband ordered something he might not normally. All we knew from the menu with our bad French, was that it had fresh spring peas and some sort of fish. It arrived, looking gorgeous with lots of beautiful green bits and some crispy bits, and strewn with foam. My husband tried a bite and the strangest look came over his face. Several more bites followed before it cleared and he asked me to try his dish. After I did, he asked me what it tasted like. If I’d had my eyes closed I would have thought I was home in Chicago eating my mom’s tuna noodle casserole! Delicious, but not what we were expecting… Reply

  • Jenne
    November 30, 2018 4:34pm

    Couldn’t you just brown the zucchini in the skillet and save having to dirty the sheet pan? Reply

    • November 30, 2018 4:45pm
      David Lebovitz

      I suppose you could, but you’d need a fairly large skillet (or cook them in two batches) as the zucchini may overload a regular-size skillet. They do shrink down during cooking, hence starting off with the sheet pan. But if you do try it by sauteeing the squash, let us know how it turns out! Reply

  • Jan
    November 30, 2018 4:38pm

    you forgot the cream of mushroom soup and a can of fried onions on top. American cooking at its best. Reply

  • K Gaylin
    November 30, 2018 4:47pm

    You had me at tuna and casserole. It’s old school and comforting but the zucchini is inspired! While I grew up with Campbell’s cream of mushroom soup, the sodium content is high so I make my own bechamel and vary the types of mushrooms. Some cream cheese in the sauce makes it even richer. I happen to love canned tuna so another way of kicking up an old favorite is most welcome. Reply

  • Elizabeth T
    November 30, 2018 4:58pm

    Love Six Seasons and the braised celery is outstanding, i make a batch and serve as a side dish when warm, then keep it in the fridge and add to my green salad throughout the week. Also and excellent addition to potato salad. Reply

  • Cindy
    November 30, 2018 5:20pm

    This looks delicious! Do you have any recommendations for good brands of oil-packed tuna that are available in the US? I also very much enjoyed the link to the YouTube video about the GE toaster oven. Have a nice day! Reply

    • MJ Wilheim
      November 30, 2018 5:49pm

      I buy this from Amazon:
      Tonnino Tuna Ventresca,In Olive Oil.
      Pricey, but way better than even the best supermarket brands in olive oil. Reply

    • Deanna
      November 30, 2018 6:11pm

      Is there a Trader Joe’s near you? They sell tuna packed in olive oil but they do add sea salt so you will have to check if there is one without sea salt or you will have to adjust your recipe. Reply

      • Cindy
        December 1, 2018 2:38am

        Thank you for the recommendation! I will start with the less expensive Trader Joe’s option, and perhaps work my way up to Tonnino. Reply

  • vivien
    November 30, 2018 5:45pm

    I still have that Toast R Oven – works like a charm!
    Thanks for the recipe… Reply

  • Rachel
    November 30, 2018 5:48pm

    Where did you get your forks? Reply

  • Carol-Ann Dearnaley
    November 30, 2018 5:51pm

    At last! A tuna casserole without the carbs! As a real fan of tuna melts, this recipe looks like it will be a great substitute. Reply

  • November 30, 2018 6:43pm

    I bought this cookbook after all the fuss last year at IACP, when it was removed as Cookbook of the Year. (See https://diannej.com/2018/outcry-after-iacp-ceo-wins-iacp-cookbook-of-the-year/) Afterwards people kept telling me how much they loved this cookbook and what a shame it was. I’ve enjoyed the recipes I’ve tried, especially the chart galette with the nut-enhanced crust. Since you like tuna, there’s a recipe for a tuna spread in the front that is magnificent with vegetables. Now I’ll have to try this tuna recipe! Reply

  • lola
    November 30, 2018 7:04pm

    how funny, i literally made tuna melts last night and thought about how i am generally completely against dairy and seafood except for tuna melts and tuna casserole! my best kept secret ingredient for tuna salad: relish. Reply

  • Cece Noll
    November 30, 2018 10:06pm

    If you want some vegetable cookbooks that are inspired, I suggest the ones by Deborah Madison, namely Greens Cookbook, The Savory Way, and Field of Greens, her first three. You probably know her from your days in SF. I think these books are great.

    I adore your posts and you! Reply

  • Kari
    November 30, 2018 11:41pm

    No garlic??

    Did you forget or was intentional? Reply

  • Amanda Beresford
    December 1, 2018 12:48am

    Thanks David, this looks excellent! And, sorry all you carb-phobes, I still make tuna casserole with a handful of pasta, or with rice, as my mother used to. And homemade béchamel, parsley, sliced hard-boiled eggs, and mushrooms; it’s the ultimate comfort food. But I will definitely try it with zucchini. On veggie cookbooks, I love Ottolenghi and Nigel Slater. Reply

    • Sheila
      December 1, 2018 1:56am

      Nigel Slater’s stuffed capsicum,yum! Reply

  • Claudine
    December 1, 2018 6:30pm

    I didn’t have any tuna ‘in oil’ so I improvised and added blobs of pesto instead… and while I was there, I also dropped a few blobs of fromage frais before topping with the grated cheese…
    Incongruous? Perhaps… But recommended! :) Reply

  • Margaret
    December 1, 2018 11:06pm

    I really like your Le Creuset gratin baking dish — maybe Santa will bring me one. It must be the 1.5 qt. size? Reply

  • Susan
    December 2, 2018 1:59am

    Oh David, I do love your website, your recipes and your all ’round Bon Vivant approach to life, food and the pursuit of culinary OMGness………..however, I must part company with you here. Anything that starts with tuna and casserole is a recipe( no pun intended) for disaster. I have never in my many years made tuna casserole of any kind. I am, as are you, a New Englander. Crimes against tuna are just not on. Forgive me for this digression as you are, otherwise, an absolute delight! Reply

    • Linn
      December 2, 2018 6:51am

      I have to admit that I thought the same thing when I first saw the title, but after I read the recipe I’ve got to try it. And it is a recipe that comes from a wonderful cookbook that won IACP cookbook of the year. One (of the many) things I love about you David is that you don’t take food and cooking so seriously that you can’t have fun with it. Reply

  • December 2, 2018 9:59am
    David Lebovitz

    Elizabeth T: Yes, I’m looking forward to trying more recipes from this book. It’s excellent.

    Kari: There’s no garlic in the recipe but you could certainly add some, sauteeing it with the scallions.

    Dianne: That snafu was unfortunate but the book really is one of the best books I’ve seen and owned, regardless of how that played out. I felt sorry for the author who did such a good job, but the book deserves all the accolades.

    Rachel: They’re from a set of silverware someone kindly gifted me. The name escapes me but it was extremely nice of them to give me the entire set! : ) Reply

  • Nan
    December 2, 2018 4:21pm

    Would there be a fresh fish to substitute tinned tuna with? Reply

    • December 3, 2018 7:10pm
      David Lebovitz

      You could use fresh tuna or bonita, I suppose, or salmon. (Or maybe something like bluefish or halibut?) If you do it with fresh fish, I’d be interested in knowing what you ended up using, and how it came out. Reply

  • Teddi
    December 3, 2018 3:22am

    We will be trying this tonight. It looked tasty when it went in the oven. As a baby boomer, I had to add some frozen peas for color and authenticity. There are some customs that must be adhered to. Reply

  • John Nettleton
    December 3, 2018 4:25am

    A total hit at table full of skeptics! Thank you Reply

  • Susan
    December 3, 2018 6:32pm

    I adore this book–one of my favorites that I got for Chanukah last year (the Israeli-Spiced Tomato Salad, or whatever it is called, was a huge hit at a summer barbecue a few months ago. I made it with beautiful heirloom tomatoes from the farmer’s market and it was perfect.) Everything I’ve made from this book has been delicious. Somehow I missed this recipe, but tuna melts are my big guilty pleasure food–and being celiac I have to eat them on GF bread, and it really isn’t the same. On zucchini? Mmmmm. I’ll spring for the good tuna. ;) Thanks for sharing your variations, David. Reply

  • Tobie
    December 3, 2018 6:41pm

    I love tuna melts too! It’s hard to find a really good one these days.
    I usually use tuna packed in water to save on some calories. Why do you use the oil packed type? Reply

    • December 3, 2018 7:08pm
      David Lebovitz

      I think most of the oil-packed tunas taste better, and would remain moister after baking (tuna sandwiches have mayo so that usually isn’t an issue) but if you want to use water-packed tuna, you could. If you do, let us know how it turns out ~ Reply

  • Susan Manegold
    December 4, 2018 2:26am

    I love this recipe. What is your opinion about using cauliflower,?
    Thanks Reply

  • Sharon Mumby
    December 4, 2018 4:24am

    Divine…I sauteed the zucchini, I didn’t have 2 cups of spring onions so I just used regular onions… with garlic and thyme… just used what I had…delicious!! Thank you Daveed again Reply

    • December 4, 2018 9:19am
      David Lebovitz

      Thanks for letting us know! Reply

  • Candace Hale
    December 4, 2018 2:13pm

    I made this recipe last night. It was cold and snowing here. For me this really was a perfect plate of delicious and healthy comfort food. In the south, where I grew up, one of my mother’s secrets to crispy fried green tomatoes with the coating still attached was to salt bleed them…
    I really liked how the zucchini held up in this dish because of that process. Also I haven’t made tuna casserole in years because of the unhealthy noodle aspect…
    Thank you for such a simple but carefully thought out and perfectly executed dish… Reply

  • tonyboloni
    December 5, 2018 7:05pm

    This is also delicious using a well drained, then rinsed, can of cannellini beans instead of tuna.

    Improvised when I discovered then cans of tuna I thought were in the pantry were not. Reply

  • Amy Below
    December 9, 2018 10:27pm

    Made this dish for the final night of Hanukkah here in Paris (accompanied by latkes, of course). A new custom is born! I hadn’t treated zucchini like that before and was truly amazed at how much water came out! I did add garlic to the scallion mixture– not too much, but I didn’t see how I couldn’t! Reply

  • December 10, 2018 4:26pm

    I like your Le Creuset gratin baking dish — maybe Santa will bring me one. It must be the 1.5 qt. size? Reply

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