In a medium bowl, whisk together eggs and milk. Set aside.
Melt butter in a large oven-proof skillet over medium-high heat. Add onions and bell peppers and cook for 3-4 minutes, or until softened. Add garlic and cook for an additional minute.
Pour egg mixture into the skillet and season with Italian seasoning, salt, and pepper. Sprinkle with cheese and cook for 3-4 minutes, or until eggs are set on the bottom.
Transfer skillet to the preheated oven and bake for 10-12 minutes, or until eggs are completely set.
Remove from oven and let sit for 5 minutes before serving.
Interesting Facts
The frittata is an Italian-style omelette that is made with beaten eggs, vegetables, and cheese.
Frittatas can be served hot or cold and are often used as a vehicle for leftovers.
Frittatas are a great way to get extra vegetables into your diet.