Method. Preheat the oven to 350 degrees F. Coat a 9-inch deep-sided pie pan with cooking spray. Evenly sprinkle 2 tablespoons of the breadcrumbs into the pan. Add the onion and 1/8 teaspoon salt and cover the skillet. Cook until the onions soften without color. Stir in the chopped tomatoes and cook for 1 minute. Transfer to a medium bowl and set aside. Meanwhile, add the eggs, egg whites, ricotta, milk, the remaining 1/3 cup breadcrumbs and 3/4 teaspoon salt to a blender until well combined and smooth. Stir in the sliced basil and the onion-tomato mixture. Pour the egg mixture into the prepared pie pan. Sprinkle with the mozzarella. Arrange the sliced tomatoes around the top. Bake until the eggs are set and the cheese is lightly browned. Let stand for 10 minutes to complete the cooking process. Garnish with the fresh basil sprig.