Spinach & Swiss Frittata

Heat broiler. Heat the oil in a large nonstick skillet over medium heat. Add the mushrooms and scallions, and cook, stirring occasionally, for 5 minutes. Meanwhile, in a medium bowl, whisk together the eggs and 1/4 tsp each salt and pepper. Stir in the spinach, cheese, and tomato. Add the egg mixture to the skillet and stir to distribute the ingredients. Cook, covered, over medium-low heat, until set on the bottom and sides (it will still be runny in center), about 4 minutes. Wrap the skillet handle with foil. Broil frittata until center is firm, about 2 minutes. Sprinkle the top with parsley and scallions, if desired.