Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add onion, squash, broccoli and pepper to pan; sauté 4 minutes or until veggies are tender.
Sprinkle 25 g shredded parmesan cheese in a 9-inch pie plate coated with cooking spray. Top with veggie mixture. Top veggie mixture with Spinach
Combine remaining 25 g parmesan cheese, egg, egg whites, cottage cheese, mozzarella cheese and milk in a large bowl; stir with a whisk.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and baking powder in a small bowl, stirring with a whisk. Add flour mixture to egg mixture, stirring with a whisk until blended. Pour egg mixture over spinach and veggie mixture. Bake at 350° for 45 minutes or until a knife inserted in center of quiche comes out clean.