When making a zucchini frittata, you start by slicing your zucchini into thin rounds and fry them until soft in olive oil. I like to brown them just slightly—not too much—and actually let them get pretty soft—but not mushy—to emphasize their natural sweetness.
Then mix the sautéed zucchini with beaten eggs, salt, pepper and lots of grated cheese. For this dish, a mild pecorino (such as a pecorino toscano) does nicely, as would grana padano or parmigiano-reggiano. Of course, you can get a bit crazy and try something entirely different, but I'd avoid a cheese that's too sharp, as it would overwhelm the delicacy of the zucchini.
The mixture goes into a skillet to fry in a bit of olive oil. As explained in the master recipe, there are different methods for cooking the top of a frittata once the bottom has browned. This time, feeling a bit lazy, I just ran the skillet under a broiler for a few minutes, until the top was nice a golden brown.