Cook until the bottom of the frittata has set and the top is nearly cooked through, about 3-5 minutes. Using a spatula, loosen the bottom of the pancake. Peel back one side, and tilt the pan so that the remaining uncooked egg slides to the open surface area. Using a second spatula, gently flip the frittata. Sprinkle the cheese over the top, and cover the pan with a plate to lock in the heat. Cook for another minute or so until the cheese is melted and the underside of the frittata has set. Slide the frittata onto a round plate and serve immediately.