Prepare the Baking Dish

Grease a 9×13-inch glass baking dish thoroughly with butter or nonstick spray to prevent sticking.

Layer the Bread

Cut the white bread into cubes and spread them evenly across the bottom of the prepared dish.

Add Sausage and Cheese

Brown the pork sausage in a skillet until fully cooked and crumbly. Drain any excess grease. Sprinkle the cooked sausage evenly over the bread cubes. Then sprinkle the grated sharp cheddar cheese over the sausage.

Mix the Egg Custard

In a large mixing bowl, crack and beat the eggs. Add the milk, dry mustard, and salt. Whisk until fully combined and smooth. Season with freshly ground black pepper to taste.

Combine and Soak

Slowly pour the egg mixture over the layered bread, sausage, and cheese. Ensure all bread is moistened by the egg mixture.

Let Sit (Optional)

For best results, cover the dish and refrigerate overnight. This helps the bread absorb the custard and bake more evenly. (Optional but recommended.)

Bake the Casserole

Preheat the oven to 350°F (175°C). Bake the casserole uncovered for about 50 minutes, or until the top is puffed, lightly golden, and the center is fully set.

Serve

Remove from the oven and let rest for 5 minutes. Cut into squares and serve warm.