One key difference between a frittata and an omelet is that in a frittata, all the ingredients are added to the eggs, and then everything is cooked together. You can add any combination of ingredients that you like, as long as the additions are cooked if needed beforehand (and cooled briefly before adding to the eggs).
Ingredients
½ cup chopped fresh spinach
½ cup diced red pepper
olive oil
6 eggs
2 oz aged cheddar cheese, grated
salt and pepper to taste
Instructions
Saute the peppers and spinach briefly in olive oil, then remove and let cool.
Beat together the eggs and grated cheese, and mix in the spinach and peppers.
Heat olive oil over medium heat in a large oven-safe skillet (a 12 inch skillet is good). Pour in the egg mixture.
Let cook undisturbed for about 10 minutes, until the bottom has set. While the eggs are cooking, turn on your broiler.
Transfer the pan to the broiler, and cook until the top is golden and puffy. This will only take a minute or so, so keep a very close eye.
Remove from the oven, cut into wedges, and serve.
Notes
I like to finish my frittata under the broiler, because I'm usually pretty hungry by the time they are done. But if you prefer, you can bake them in the final step. If you do this, preheat the oven to 350 degrees before the first step, and at the end, bake the frittata until completely set and not runny, about 10-20 minutes.
Recipe by Sprung At Last at https://sprungatlast.com/2013/04/red-pepper-spinach-and-cheddar-frittata/