Overnight Breakfast Casserole with Sausage and Cheese
Easy make-ahead breakfast casserole with spicy sausage, eggs, spinach, and two types of cheese. Prep the night before and bake in the morning for a stress-free, crowd-pleasing breakfast.
Ingredients
- 2½ cups seasoned croutons
- 1 pound spicy pork sausage
- 4 large eggs
- 2¼ cups whole milk
- 10.75 oz can condensed cream of mushroom soup undiluted
- 10 oz package frozen chopped spinach thawed and squeezed dry
- 4.5 oz can mushrooms drained and chopped
- 1 cup sharp Cheddar cheese shredded
- 1 cup Monterey Jack cheese shredded
- ¼ teaspoon dry mustard
- 2 sprigs fresh parsley for garnish
Instructions
- Prepare the baking dish: Grease a 9x13 inch baking dish well with butter or cooking spray. Spread seasoned croutons evenly across the bottom.
- Cook the sausage: In a medium skillet over medium heat, brown the pork sausage for 8-10 minutes, breaking it up with a wooden spoon until no pink remains. Drain excess fat completely. Spread cooked sausage evenly over the croutons.
- Make the egg mixture: In a large bowl, whisk together eggs and milk until frothy and well combined. Add the undiluted condensed cream of mushroom soup. Thaw the frozen spinach completely, then squeeze it in a clean kitchen towel until completely dry with no moisture remaining. Add the dry spinach and drained, chopped mushrooms to the egg mixture.
- Add cheese and seasonings: Stir both shredded cheeses and dry mustard into the egg mixture. Mix thoroughly until everything is well combined - the mixture will be thick and chunky.
- Assemble and refrigerate: Pour the egg mixture evenly over the sausage and croutons. Use a spatula to spread it around, ensuring all croutons are moistened. Cover tightly with aluminum foil or plastic wrap. Refrigerate for at least 8 hours or overnight (up to 24 hours for best results).
- Bake: Preheat oven to 325°F (165°C). Remove cover from casserole. Bake for 50-55 minutes until the center is set (no jiggling), top is golden brown, and a knife inserted in the center comes out clean.
- Serve: Let rest for 5 minutes. Garnish with fresh parsley sprigs. Cut into squares and serve hot.
Notes
Spinach preparation is crucial: The spinach MUST be completely dry. After thawing, squeeze it in a clean kitchen towel until no more water comes out. Excess moisture will make the casserole watery.
Cheese tip: Freshly shredded cheese from a block melts better and tastes better than pre-shredded cheese.
Sausage substitutions: Use mild pork sausage for less heat, or turkey sausage for a leaner option.
Best results: Make this 24 hours ahead instead of just 8 hours for better flavor development and texture.
Temperature trick: Remove casserole from fridge while the oven preheats for more even cooking.
Storage: Store leftovers covered in the refrigerator for 3-4 days. Reheat individual portions in the microwave for 90 seconds, or reheat multiple portions in a 300°F oven until warmed through.
Freezing: Freeze assembled but unbaked casserole for up to 2 months. Thaw completely in refrigerator overnight before baking as directed.
Doneness test: The casserole is done when the center reaches 160°F on an instant-read thermometer, or when the center is set and doesn't jiggle when gently shaken.
Cheese tip: Freshly shredded cheese from a block melts better and tastes better than pre-shredded cheese.
Sausage substitutions: Use mild pork sausage for less heat, or turkey sausage for a leaner option.
Best results: Make this 24 hours ahead instead of just 8 hours for better flavor development and texture.
Temperature trick: Remove casserole from fridge while the oven preheats for more even cooking.
Storage: Store leftovers covered in the refrigerator for 3-4 days. Reheat individual portions in the microwave for 90 seconds, or reheat multiple portions in a 300°F oven until warmed through.
Freezing: Freeze assembled but unbaked casserole for up to 2 months. Thaw completely in refrigerator overnight before baking as directed.
Doneness test: The casserole is done when the center reaches 160°F on an instant-read thermometer, or when the center is set and doesn't jiggle when gently shaken.