Instead of the eau-de-vie or grappa, you could use amaretto or another liqueur that you have on hand. If you are avoiding alcohol, you could use more water or hot tea for the 3 tablespoons of eau-de-vie.
I used fine polenta, but if you have regular polenta on hand, you could use that. Similarly, it'll probably work with stone-ground cornmeal, although it's best to use one that's coarsely ground for maximum crunch.
Although these get shaped into diamonds, you could roll them out and cut them into shapes using a cookie cutter.
Storage: The cookies can be kept up to one week in an airtight container at room temperature.