Beat the eggs in a large bowl. Add the cooked onions, the roasted peppers cut into strips, salt and pepper to taste.
In a large omelet pan heat up some olive oil with the butter. When very hot, pour in the egg mixture and cook until the frittata is slightly “runny.” Place the frittata on an ovenproof dish.
Cover with the sliced Taleggio cheese. Place in a hot oven at 375°F for 5 minutes, or until the Taleggio cheese has melted. Serve immediately.
Serves 4.
