Make-ahead sausage and egg breakfast casserole layers savory sausage, shredded potatoes, vegetables, eggs, and cheddar in one pan. It can go straight into the oven after assembly or rest in the refrigerator overnight for a low-stress breakfast.
Refrigerated hash browns form a substantial base without needing to toast bread. Cooking the sausage and vegetables first removes excess moisture and helps every slice hold together cleanly.

Prep: 20 minutes Cook: 45 minutes Optional chill: up to 12 hours Total: 1 hour 10 minutes, plus optional chill Yield: 8 servings
Ingredients
- Nonstick cooking spray or softened butter, for the dish
- 12 ounces turkey or pork breakfast sausage
- 1 small red bell pepper, diced
- 2 packed cups baby spinach, roughly chopped
- 20 ounces refrigerated shredded hash brown potatoes
- 10 large eggs
- 1 cup whole or 2% milk
- 1 teaspoon Dijon mustard
- 1/2 teaspoon garlic powder
- 1/2 teaspoon fine salt
- 1/4 teaspoon black pepper
- 1 1/2 cups shredded sharp cheddar cheese, divided
- 2 tablespoons sliced green onions, optional
Directions
- Lightly grease a 9-by-13-inch baking dish. Heat a large skillet over medium heat. Add the sausage and cook for 6 to 8 minutes, breaking it into small crumbles, until fully browned with no pink remaining. Transfer to a paper-towel-lined plate.
- Pour off excess fat, leaving about 1 teaspoon in the skillet. Add the bell pepper and cook for 3 minutes. Add the spinach and stir for 1 to 2 minutes, until wilted. Remove from the heat.
- Spread the hash browns evenly in the baking dish. Top with the cooked sausage, pepper, spinach, and 1 cup cheddar.
- Whisk the eggs, milk, Dijon, garlic powder, salt, and pepper until no streaks remain. Pour evenly over the casserole. Sprinkle with the remaining 1/2 cup cheddar.
- Bake immediately in a 375°F oven for 40 to 45 minutes, or cover and refrigerate up to 12 hours. If chilled, uncover while the oven heats and expect the bake to take 45 to 55 minutes.
- The casserole is ready when the center is set and reaches 160°F. Rest for 10 minutes, then top with green onions and cut into 8 pieces.
Why this recipe works
Precooking controls moisture. Browning sausage and wilting spinach prevents grease and vegetable liquid from pooling around the eggs.
A short rest improves slices. Ten minutes lets the hot egg mixture finish setting so the portions cut cleanly without overbaking.
Helpful variations
For extra vegetables, add 1 cup chopped mushrooms with the bell pepper and cook until their released liquid evaporates. Pepper Jack can replace cheddar for mild heat.
To make it meatless, omit the sausage and add 8 ounces sautéed mushrooms plus another cup of spinach. Verify that frozen hash browns are thawed and squeezed dry before using them in place of refrigerated potatoes.
Common questions
Can I freeze it before baking? For the best texture, bake first, cool, cut into portions, and freeze. Raw potatoes and egg custard can release water after a freeze-thaw cycle.
Why is the center watery? Excess vegetable moisture, frozen potatoes that were not drained, or an underbaked center are common causes. Check the middle for 160°F before removing the pan.
Storage and food safety
Cook raw sausage thoroughly before assembly and wash hands and utensils after contact with it. Keep an assembled overnight casserole covered at 40°F or colder and bake within 12 hours. Cook the center to 160°F. Refrigerate leftovers within 2 hours and use within 3 to 4 days; reheat portions to 165°F. Freeze cooled portions up to 2 months.
Estimated nutrition
Per serving, estimated: 330 calories, 21 g protein, 20 g carbohydrate, 19 g fat, 2 g fiber, 3 g sugar, and 650 mg sodium. This is an estimate based on the listed ingredients; brands and portions change the result.
Helpful kitchen gear
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A meatless make-ahead egg option
For a vegetable-forward breakfast without potatoes or pastry, try this crustless spinach mushroom quiche with feta.
