Preheat oven to 375°. Spray a 15¾ x 11¾ -inch baking pan (inside measurements) with non stick cooking spray. Sprinkle on the bottom of the pan the onion, red and green bell peppers and ham. In a large bowl whisk together the eggs, milk, salt and pepper. Pour over ham mixture. Bake 35 minutes or until a knife inserted into the center comes out clean.
OPTIONAL TOPPINGS: Salsa, cheese, scallions or fresh tomatoes.