Frittata di Cipolle: Onion Frittata

I have always loved a simple frittata, but when I first read the recipe for frittata di cipolle (onion frittata) in Leah Olsen’s book Portico: Cooking and Feasting in Rome’s Jewish Kitchen, I wondered if it might be too simple. It contains just four ingredients: eggs, onions, extra-virgin olive oil, and salt. But, as Leah points out in her headnote, “he…