many of my frittata recipes make an entire pan for serving 4-6 people, except for this version, which is a great meal for one. the recipe can be easily doubled or even expanded for more, as the ingredients are easily increased.
begin by placing a 1 cup ovenproof baking dish on a rimmed baking sheet, and place in the oven. preheat the oven to 450 degrees. while the oven is heating, whisk together 1 large egg and 2 large egg whites. add 1 tablespoon of grated Gruyere cheese, 2 teaspoons of milk, 1 teaspoon salt, and a pinch of ground pepper. set aside.
in a small skillet, heat one teaspoon of olive oil and cook 1/2 small sliced shallot or onion, and cook until softened, about 2 minutes. add 1 1/2 cups of baby fresh spinach, and cook until wilted, about 2 more minutes. season with salt and pepper to taste. add this mixture to the egg mixture.
remove the heated dish from the oven, and coat with cooking spray. immediately pour the egg mixture into the dish and top with 1 tablespoon of grated cheese.
bake until the frittata is puffed up and golden brown about 15 to 18 minutes. serve with a side salad.
i usually use a metal serving plate as the baking dish is very hot out of the oven. the frittata will deflate a bit , but the taste is excellent.