Melt butter in a large skillet over medium heat. Add onion, ham, and bell pepper, and sauté until vegetables are softened, about 5 minutes. Season with oregano and garlic powder, and remove from heat.
In a large bowl, whisk together eggs, milk, salt, and pepper. Stir in ham mixture, and pour into a 9x13 inch baking dish.
Bake in preheated oven for 20 minutes. Sprinkle cheese over top, and continue baking until eggs are set, about 10 minutes more.
Interesting Facts
An omelet is a type of egg dish that is typically made with beaten eggs and cooked in a skillet.
The word "omelet" comes from the French omelette which means "little egg cake".
The omelet is believed to have originated in France in the early 19th century.