Yes, an oven-safe skillet can be preheated in the oven at 350°F (180°C). When the skillet is hot and well-greased with melted butter and oil, pour in the egg mixture, cover with foil, and bake for 6 to 8 minutes. Uncover, add any filling to one half of the baked omelette, fold in a half-circle shape, and bake uncovered until the center is cooked.