Add olive oil to a skillet over medium heat. Add the onions and cook for about 10 minutes. Stirring occasionally.
Add the red peppers and cook another 5 minutes, stirring occasionally.
Add the zucchini and salt & pepper and cook another 3 minutes, stirring occasionally.
While your veggies are cooking, whisk the eggs and Parmesan cheese. Pour the egg mixture on top of the cooked veggies and continue to cook on the stove top for about 3 minutes. Do not stir.
Pre-heat the oven to 400℉ and place the skillet in the oven. Bake for 15 minutes. Let cool 5 minutes before cutting into slices.