Shiitake, Fontina, and Prosciutto Frittata
- Preheat oven to 350 degrees.
- Melt 3 tablespoons butter in 12" nonstick ovenproof skillet over medium heat. Add shallots; saute 2 minutes. Add prosciutto; saute until almost crisp, about 3 minutes. Add mushrooms, saute until brown and tender, about 6 minutes. Cool mushroom mixture in skillet 10 minutes.
- Whisk eggs, 1 cup grated Fontina cheese, parsley, salt and pepper in large bowl. Stir in mushroom mixture. Melt 1 tablespoons butter in same skillet over medium heat. Pour egg mixture into skillet. Cook without stirring until bottom and sides are set (top will be undercooked), about 10 minutes.
- Place skillet in oven and bake frittata until top is set, about 20 minutes.
- Preheat broiler. Sprinkle frittata with remiaining 1 cup cheese. Broil until cheese melts, about 2 minutes. Using heatproof spatula, loosen frittata on all sides. Slide onto platter.
- Can be made 2 hours ahead. Let stand at room temperature.