Sausage and Cheddar Breakfast Casserole

Ingredients:

• 1 tbsp. unsalted butter, for greasing
• 6 slices white bread
• 1 lb. bulk breakfast sausage, casing removed
• 10 oz. grated cheddar cheese
• 2 cups milk
• 1⁄2 tsp. dry mustard
• 6 eggs, lightly beaten
• Kosher salt and freshly ground black pepper, to taste

Source