Is it a proper frittata if you don’t start it in a skillet on the stove? Perhaps these are just baked eggs. Either way, they’re delicious.
Preheat your toaster oven to 375° F (it was in the mid-80s today, too hot for the big oven). Saute two small onions, diced, in a little olive oil. While they are turning soft and golden, wash and trim about 10 cups of swiss chard, and then chop it roughly. Add the chard to the pan, cook until wilted. Let it cool a bit. Beat a dozen eggs with 4 to 8 oz. of shredded Gruyère, add the chard mixture, and stir. Pour into a greased pan (I used the one that came with my toaster oven, which is about 9.5″x11″) and bake for 25 minutes, or until eggs are set.
Once you’ve cooled the frittata, slices can be individually frozen.