Eggs, Zucchini, & Mushroom Casserole

cooking spray
1 1/2 cups zucchini, sliced
1 1/2 cups mushrooms, sliced
1/2 cup sweet red peppers, diced
1/4 cup onion, chopped
6 eggs, separated
3 tablespoons flour
1/4 teaspoon salt
1/4 teaspoon pepper
1 1/4 cup milk, heated
1/2 cup cheddar cheese, grated
parsley sprigs (optional)

Preheat oven at 375° degrees F. Evenly coat a 10 inch skillet with spray. Add zucchini,
mushrooms, peppers and onion. Cover and cook over medium heat until peppers are crisptender.
Set aside. Meanwhile, evenly coat 15 x 10 inch jelly roll pan with spray. Line with wax
paper and spray again. Set aside.