1. Butter a 9-inch (23cm) loaf pan. Dust the inside with polenta, and tap out any excess. (Note: The pan I used has a nonstick finish. If you want to make sure the cake comes out nicely you may want to cut a rectangle of parchment paper and fit it into the bottom of the pan after you prepare it, especially if using an unfinished loaf pan.) Preheat the oven to 350ºF (180ºC).
2. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, sugar and lemon zest at medium-high speed, until it’s light and fluffy, about 3 minutes. (You can also make this in a large bowl, beating the butter and sugar by hand.)
3. Add the eggs one at a time, stopping the mixer after each addition to scrape down the sides of the bowl. Mix in the liqueur and almond extract.
4. In a medium bowl, whisk together the polenta, ground almonds, flour, baking powder, and salt, until there are no lumps. Gradually mix the dry ingredients into the creamed butter mixture, just until well-combined. Do not overmix.
5. Scrape the batter into the pan, smooth the top, and bake the cake until it is golden brown on top and a toothpick inserted into the center comes out almost clean, perhaps with just a few crumbs attached, 45 to 50 minutes. Let cool on a rack for about 30 minutes, then run a knife along the outside of the cake to loosen it from the pan and tip the cake onto the rack. Let the cake cool completely before icing.
6. To glaze the cake, mix the powdered sugar with the orange juice and orange liqueur until the glaze is thick, but still runny – not too watery, but as thick as a milkshake. If necessary, add a bit more sugar if it’s too thin, or add a bit more liquid if it’s too thick. You can try smoothing a bit over the cake to see if it’s the right consistency for drizzling and dripping down the sides before glazing the entire cake.
7. Spoon the glaze over the cake, encouraging the glaze to run down the sides by nudging it towards the edges with the back of the spoon or a metal spatula.