I don't often make omelettes but there's this one recipe I like, mostly because it's done in the oven and cooks up so fluffy. There isn't a 'set' recipe, it's more of one of 'those' that you just toss stuff into a large bowl so all amounts are estimates. Here's my favourites;

6 eggs, beaten
1/2 cup of milk (sometimes more or less, depending on how many eggs I'm using)
green peppers, chopped into good sized pieces
red peppers, chopped into good sized pieces
1 onion, finely chopped
sprinkle of coarse black pepper
1 - 2 tbsp of butter, divided up into small pieces
a few sliced mushrooms, if desired
ham, cubed into not-too-big pieces
2 cups shredded mozzarella cheese, stirred in (reserve about 1/4 cup to sprinkle over the top)

Stir all ingredients together and pour into a greased baking dish. Sprinkle the reserved amount of cheese over the top and put (uncovered) into a 300 F oven. Cook until a light golden brown around the edges and firm in the middle. Slice into pie wedges and serve.

Painted on a 1/4 sheet of Arches 300 lb CP Paper in watercolour. Framed in a gold metal frame with a white mat, it's now hanging in my kitchen! (This was also painted as an aceo.)