01 -
Grease a 9×13-inch baking dish. Place the croissant pieces evenly in the dish.
02 -
Sprinkle the cooked sausage and shredded cheese over the croissants.
03 -
In a large bowl, whisk together the eggs, milk, dry mustard, salt, and black pepper until well combined.
04 -
Pour the egg mixture over the croissant, sausage, and cheese layers, pressing down gently to ensure the croissants soak up the liquid.
05 -
Cover the dish with plastic wrap and refrigerate overnight or for at least 2 hours.
06 -
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.
07 -
Allow the casserole to cool for a few minutes before slicing. Serve warm.