Step 1

Preheat the oven to 400º.

Step 2

Heat the oil in an ovenproof skillet over medium-low heat. Add the onion, if desired, and saute with salt and pepper to taste for about 5 minutes.

Step 3

Add the red pepper; sauté for 5 minutes, stirring frequently. Remove the vegetables; set aside.

Step 4

In a small bowl, vigorously whisk the eggs with salt and pepper and basil or thyme, if desired.

Step 5

Spray the skillet and heat over medium heat. Add the eggs and cook for 1 minute. Arrange the onions, if using, over the eggs and arrange the red pepper in a pinwheel shape (or scatter it). Sprinkle on the cheese, if desired.

Step 6

Bake the eggs on the middle rack of the oven for about 14 minutes, or until set.

Step 7

Place the skillet under the broiler for 1 to 2 minutes to help the frittata rise. It should be slightly moist, but a toothpick inserted in the center should come out dry.

Step 8

Cut into wedges and serve hot or at room temperature.