This frittata is so easy to make and it's filled with mushrooms, spinach, sweet potatoes, and delicious basil pesto! It's perfect for meal prep too!
Preheat oven to 375℉. Liberally grease a 10 inch cast iron skillet or baking dish with coconut oil or cooking spray.
Preheat a large skillet to medium-high heat and add olive oil. Add mushrooms and sauté for 5-6 minutes or until golden. Add the spinach and stir until just wilted. Remove from heat. Season with a pinch of salt and pepper. Set aside to cool slightly.
In a large bowl, whisk together the eggs and egg whites until combined. Add the sweet potatoes, pesto, and mushrooms and peppers once slightly cooled. Add the salt and pepper and whisk again to combine. Pour mixture into skillet or baking dish and bake for 25-30 minutes until eggs are set and slightly golden on the edges. Serve with extra pesto and avocado!