Spinach, Onion, and Swiss Frittata

Supplement your morning diet with a delicious frittata; eggs contain more protein, and vegetables become tender and appetizing. Get creative with your frittata – try the spicy jalapeno and cheddar, or the Swiss-style ham. This frittata is easy to feed a family of four.
Preheat the oven to 400 degrees.Preheat a 10-inch nonstick skillet over medium-high heat. Add the butter; stir to coat. Add the onion; simmer for 10 minutes or until soft. Add the spinach; cook for 2 minutes, stirring occasionally, until the spinach wilts.Mix the eggs, salt and pepper. Pour the egg mixture over the vegetables in the pan; cook until the edges start to set, about 2 minutes. Gently lift the edges of the egg mixture, tilting the pan so that the raw egg mixture is in contact with the pan. Cook for 2 minutes or until the egg mixture is almost set. Sprinkle with cheese.Bake at 400 ° C for 8 minutes or until the center is set. Transfer the frittata immediately to a serving platter; cut into 6 slices.