Caramelized Onion, Mushroom, And Quiche With Oat Crust

Directions

Preheat oven to 400°F. Spray a 9-inch pie dish with cooking spray. To prepare crust, put the oats, flour, and salt in a food processor and pulse to combine. Add the butter and pulse, until you get a pebbly course texture. Add buttermilk and pulse more to combine. Form mixture into a ball, then flatten out to fit into the pie dish. Bake for about 9 minutes, then let cool. To prepare filling, heat 2 teaspoons of oil in a large nonstick pan over medium-low heat. Add onion and cook, stirring occasionally, until caramelized, about 20 minutes. Transfer onions to a bowl. Add remaining 2 teaspoons of oil to the pan, along with the mushrooms, then cook over medium-high heat, stirring occasionally, for about 6 minutes. Add onions back to the pan, stir in the salt, pepper, mustard, and thyme. In a bowl whisk together eggs, egg whites, and milk. Sprinkle cheese onto the pie crust. Top with the mushroom-onion mixture and pour the egg mixture on top. Reduce oven temperature to 350°F. Bake for 35 minutes, or until knife inserted in the middle comes out clean. Let stand for 5 minutes before cutting into 6 wedges and serving. Enjoy!