Italian Garden Frittata

Ingredients

• 6 egg whites
• 4 eggs
• 1/2 cup grated Romano cheese, divided
• 1 tablespoon minced fresh sage
• 1/2 teaspoon salt
• 1/4 teaspoon pepper
• 1 small zucchini, sliced
• 2 green onions, sliced
• 1 teaspoon olive oil
• 2 plum tomatoes, thinly sliced