- Preheat oven to 350°F.
- Beat eggs, milk, Italian seasoning, salt and pepper in medium bowl until well blended. Add cheeses, squash, spinach and onion; mix well.
- Spray 1 (12-cup) muffin tin generously with no stick cooking spray. Spoon about 1/4 cup egg mixture into each cup. Sprinkle with tomatoes.
- Bake 20 to 22 minutes or just until eggs are set.
- Run small knife or spatula around each cup to loosen mini frittatas. Let stand 5 minutes before serving.