Ingredients
8 egg yolks
1 cup diced cremini or white mushrooms
1 cup shredded Swiss cheese (divided)
1 tbsp chopped fresh thyme (or 1 tsp dried thyme)
1/8 tsp salt
8 egg whites
1 cup pasta sauce, heated (optional)
Instructions
1 Place yolks in large bowl; whisk until blended. Add mushrooms, 3/4 cup cheese, thyme and salt; whisk until combined.
2 Place egg whites in another large bowl; beat with electric mixer until stiff peaks form.
3 Gently fold egg whites into yolk mixture, avoiding over-folding so as not to deflate whites.
4 Spray 10-inch (25 cm) ovenproof skillet with cooking spray. Pour mixture into skillet. Cook over medium heat until bottom is set, about 2 minutes. Sprinkle remaining cheese over top.
5 Place skillet in preheated 425°F oven and bake until top is puffed and golden, and frittata is set, 8 or 9 minutes. Cut in wedges and serve immediately, with warmed pasta sauce spooned over each serving, if desired.
