Overnight Breakfast Casserole for a Cold Oven Start

• Cold-start baking avoids a counter-rest step. Set the covered dish in the oven, then let oven and casserole warm together without extra planning.
• Thawed hash browns make a sturdy base without bread that can turn soggy overnight. They portion neatly with a spatula at the table.
• Browning sausage first renders excess fat and seasons the filling before it meets the eggs. Drain well for distinct layers.
• A 9-by-13-inch pan makes twelve squares for several mornings. Edges set first while the center finishes gently.

• 1 pound breakfast sausage (454 g)
• 1 medium yellow onion, finely diced (150 g)
• 1 red bell pepper, finely diced (150 g)
• 1 bag frozen shredded hash browns, thawed (680 g)
• 2 cups shredded sharp cheddar, divided (226 g)
• 10 large eggs (500 g)
• 2 cups whole milk (480 g)
• 1 teaspoon kosher salt (6 g)
• 1/2 teaspoon black pepper (1 g)
• 1 tablespoon unsalted butter, softened, for dish (14 g)

Ingredient notes

• Use fully thawed shredded hash browns, then squeeze any visible moisture from the bag before layering. Frozen potatoes release liquid as they bake; starting thawed keeps the base tender rather than watery and helps each square hold together.
• Choose regular breakfast sausage, either mild or hot, and brown it until no pink remains before assembling. Turkey sausage works too, though it may leave less rendered fat in the skillet and needs the same thorough draining.
• Ten large eggs give this casserole enough structure to cut into clean squares after resting. Whole milk keeps the custard soft; lower-fat milk can work, but the finished center will be less rich.
• A red bell pepper brings sweetness and color, while a yellow onion softens into the sausage layer overnight. Dice both pieces small so they distribute through each serving instead of creating bulky pockets.
• Sharp cheddar is deliberate here because its flavor stays noticeable beside sausage and potatoes. Shred a block if possible for smoother melting, then reserve some for the top rather than mixing all of it below.

1. 1Grease the dish

   Butter a 9-by-13-inch baking dish, including the corners and upper sides. This helps the egg layer release cleanly later and gives the potatoes a little protection against sticking while the cold dish gradually comes up to oven temperature.

   

2. 2Brown the filling

   Cook the sausage in a large skillet over medium heat, breaking it into small crumbles. Add onion and bell pepper once the sausage begins to render, then cook until the vegetables soften. Tip the mixture into a colander and drain thoroughly.

   

3. 3Build the base

   Spread the thawed hash browns evenly across the buttered dish. Scatter the drained sausage mixture over them, then add three-quarters of the cheddar. Keep the layers level, especially near the corners, so every square gets potatoes, filling, and cheese.

4. 4Whisk the custard

   Whisk eggs, milk, salt, and pepper in a large bowl until the yolks disappear and the mixture looks uniform. Pour slowly over the layers, moving across the pan rather than aiming at one spot. Press stray potatoes under the liquid with a fork.

5. 5Cover and chill

   Sprinkle the remaining cheddar over the surface, cover the dish tightly, and refrigerate overnight. The rest lets the potatoes absorb some custard and makes the unbaked casserole easier to manage when the morning schedule is moving quickly.

6. 6Bake from cold

   Place the covered cold dish in a cold oven, set it to 350°F, and bake for 35 minutes. Uncover and continue baking 25 to 30 minutes, until the center reaches 160°F. Rest 10 minutes before cutting twelve squares.

• Drain the sausage mixture in a colander. Rendered fat can pool around potatoes and make the bottom layer heavy after chilling.
• Do not use hash browns frozen solid. Thaw them in the refrigerator, then press out visible moisture with clean paper towels before layering them into the dish.
• Keep casserole covered for the first baking portion. The gentle start warms the cold center while keeping cheese from darkening before eggs set.
• Use an instant-read thermometer in the center, avoiding a sausage piece. Bake until it reaches 160°F; carryover heat alone should not finish the egg custard.
• Let casserole stand 10 minutes before cutting. The brief rest firms custard, releases steam, and gives cleaner portions than slicing immediately from the oven.

Cut the casserole into twelve squares and serve it with salsa, hot sauce, or sliced avocado on the side. A spoonful of plain Greek yogurt works like a quick creamy topping without another pan. For a fuller table, add orange wedges and a simple bowl of berries. The potato base makes it substantial enough to skip toast, though toasted English muffins are useful for anyone who wants a sandwich-style portion.