This Spicy Sausage and Caramelized Onion Breakfast Casserole is one of my favorite low carb/keto breakfasts. The sweetness of the caramelized onions are what really make this such an awesome breakfast casserole.
Melt butter in a large skillet over medium-low heat. Add onion and cook, stirring occasionally until golden, about 15 minutes. Let cool slightly.
In a second large skillet cook and crumble sausage meat. When sausage is about halfway done, add mushrooms. Continue to cook until sausage is no longer pink and mushrooms are golden brown. Let cool slightly.
In a large bowl, whisk together eggs and heavy cream. Stir in cheese, garlic powder, salt and pepper.
Transfer sausage, mushrooms, and onions to a greased 7x11-inch pan. Pour egg mixture over the top.
Bake for 40 minutes in a 350 degree oven.