Preheat oven to 350°F (175°C) and grease a 9x13 inch baking dish.

Spread day-old bread cubes across a baking sheet in a single layer. Bake for 8-10 minutes until lightly toasted.

In a large skillet, brown the pork sausage over medium-high heat. Drain excess grease and sprinkle sausage over the toasted bread cubes.

Sprinkle 1 cup of shredded cheddar cheese over the sausage and bread.

In a mixing bowl, whisk together eggs, milk, cream, salt, pepper, and mustard powder until combined.

Pour the egg mixture evenly over sausage and bread layers in the baking dish. Top with remaining cheese.

Bake casserole for 40-50 minutes until the center is set and the top is golden.

Let the casserole rest for 10 minutes before serving.