Preheat oven to 400°F (200°C).

Grease two 10-oz custard cups or individual baking dishes.

Heat an 8-inch skillet over medium-low heat.

Add margarine to the skillet.

Sauté zucchini, onion, red pepper, and garlic in the margarine until tender and slightly cooled.

In a medium bowl, beat egg whites, milk, salt, and Italian seasoning until combined.

Stir in the zucchini mixture.

Pour the mixture into the prepared custard cups or baking dishes.

Sprinkle Monterey Jack cheese and Parmesan cheese over the top.

Bake, uncovered, at 400°F (200°C) for 14 to 17 minutes, or until the top is puffy and light golden brown.

Let stand for 5 minutes before serving.