Easy Mushroom Frittata is one of the most tasty, simple dishes to satisfy any meal requirement - be it breakfast, brunch or brinner. Sauteed mushrooms, wilted spinach and creamy ricotta cheese nestled together in a bed of protein-rich soft eggs are fast and filling.
In a large bowl, whisk the eggs, sour cream, salt, and pepper until smooth. Set aside.
Melt 1 tablespoon butter and oil in an oven safe skillet over medium high heat; add mushrooms and toss to coat in the fat. Saute, stirring every 4-5 minutes, until they release their liquids and are golden brown and crisp, about 15 minutes.
Push the mushrooms to the edge of the pan. Add the onions and cook until the edges just barely start to brown, about 5 minutes.
Add the garlic and thyme to the skillet and toss to combine with the onions and mushrooms; saute, stirring constantly, for 1 minute.
Add the spinach to the skillet; saute, tossing frequently, until wilted.
Add the remaining tablespoon of butter to the skillet and let it melt. Once melted, pour in the egg mixture and gently shake the skillet to evenly distribute.
Dot the ricotta over the top of the frittata. Cook 1-2 minutes more, or until the edges of the frittata are just starting to firm up.
Transfer the skillet to the oven. Bake until the eggs are puffed but the center is just slightly soft (it will have a slight jiggle to it), 14-16 minutes.
Remove the skillet from the oven using oven mitts and place it on a cooling rack. Cool at least 5 minutes, or until the edges gently pull from the sides of the skillet.