Easy Cheesy Breakfast Casserole
["1/2 lb. bulk sausage", "1 small onion, chopped", "1 1/2 Tbsp. butter", "6 eggs, beaten", "4 oz. mushroom pieces", "1/2 tsp. salt", "dash of white pepper", "2 Tbsp. butter", "3 Tbsp. flour", "1 c. milk", "6 oz. Cheddar cheese, cubed", "dash of dry mustard"]
["Preheat oven to 350\u00b0.", "Brown sausage with onion; drain and set aside.", "Wipe out the same pan with paper towel and melt the 1 1/2 tablespoons butter.", "Add beaten eggs to the pan and scramble lightly.", "Fold in mushrooms and sausage mixture and set aside.", "In a medium saucepan, melt 2 tablespoons butter with salt, pepper and flour.", "Add milk, stirring, over low heat until smooth and thickened.", "Stir in cheese to melt.", "Add dry mustard and blend. Fold sauce into the reserved egg mixture.", "Pour into a buttered casserole dish and bake 30 minutes.", "Can be made ahead, refrigerated and heated at serving time.", "Serves 6 to 8."]
["bulk sausage", "onion", "butter", "eggs", "mushroom pieces", "salt", "white pepper", "butter", "flour", "milk", "Cheddar cheese", "mustard"]