Preparation / Directions:
Melt 2 tablespoons butter in heavy medium skillet over medium heat. Add onions and saute until tender, about 5 minutes.
Add mushrooms and saute until tender, about 5 minutes. Add Sherry and thyme and boil until almost all liquid evaporates. Remove from heat.
Heat remeaining 2 tablespoons butter in heavy large ovenproof skillet over medium heat. Beat eggs, salt and pepper in large bowl. Pour into skillet. Spoon mushroom mixture over.
Cook until eggs are almost set, but still soft on top, lifting edges of eggs and tilting pan so uncooked eggs run underneath, about 8 minutes.
Sprinkle cheese over top. Place skillet under broiler until cheese melts and eggs are completely cooked, about 3 minutes.
Transfer to platter. Serve warm or at room temperature, cut into wedges
A frittata is like a Spanish version of an omelet, but with the filling on top. You start it on the stove then finish it under the broiler. This dish is wonderful for breakfast, brunch or dinner and can be served hot or at room temperature.