Dad's Breakfast Sausage Casserole

This breakfast casserole is the make-ahead solution for Christmas morning, holiday brunch, and any time you have houseguests and don’t want to cook breakfast at 6am. Assemble it the night before, refrigerate overnight, and the only morning work is sliding it into the oven. The overnight rest is non-negotiable; the bread needs hours to fully absorb the egg-and-milk mixture and turn into custardy strata-style perfection.

Dry mustard in the egg mixture is the small detail that separates this from average breakfast casseroles. It adds savory warmth and just enough bite to cut through the richness of the sausage and cheese without tasting like mustard. Don’t omit it.

Brown the sausage thoroughly and drain off the fat before layering. Wet, undercooked sausage releases grease into the casserole during the long bake, leaving you with a soggy bottom. Brown until the sausage is fully cooked and crumbly, then drain on paper towels.

Use stale bread or set fresh bread out for an hour to dry slightly before cubing. Soft, fresh bread turns to mush in the egg mixture; slightly stale bread holds its texture and creates the right custardy-but-distinct layers.

Sharp cheddar pulls more weight than mild here. The sharp variety has more flavor compounds that survive the long bake; mild cheddar can disappear into the eggs and lose its character.

The 5-minute rest after baking is essential. The casserole continues to set as it cools and slicing too early gives you weeping wedges with runny middles.

Pro Tips

• For 8 servings, use 3 slices of bread and 8 eggs (per the recipe’s note). Scale the cheese and sausage proportionally.
• Use breakfast sausage (the loose ground variety) rather than link sausage. It crumbles into the casserole better.
• For browning, sprinkle a tablespoon of grated Parmesan over the top in the last 10 minutes for a golden crust.

Variations

• Swap sausage for diced ham or crumbled crispy bacon for different breakfast meat profiles.
• Add 1 cup of sauteéd mushrooms, peppers, or onions to the layers for vegetable boost.
• Substitute pepper jack or Gruyere for cheddar for a more sophisticated cheese profile.