Step 1

Grease a 9×13-inch baking dish. Place the croissant pieces evenly in the dish.

Step 2

Sprinkle the cooked sausage and shredded cheese over the croissants.

Step 3

In a large bowl, whisk together the eggs, milk, dry mustard, salt, and black pepper until well combined.

Step 4

Pour the egg mixture over the croissant, sausage, and cheese layers, pressing down gently to ensure the croissants soak up the liquid.

Step 5

Cover the dish with plastic wrap and refrigerate overnight or for at least 2 hours.

Step 6

Preheat the oven to 350°F (175°C). Remove the casserole from the refrigerator and let it sit at room temperature while the oven heats. Bake, uncovered, for 40-45 minutes, or until the top is golden brown and the custard is set.

Step 7

Allow the casserole to cool for a few minutes before slicing. Serve warm.