This loaded cheesy breakfast casserole brings eggs, savory breakfast sausage, peppers, greens, hash browns and a generous layer of cheese into one satisfying oven dish. It is designed for a relaxed family breakfast or a brunch table: prepare the filling, pour it into a baking dish, and let the oven do the rest.
The base is flexible. Cheddar gives the casserole its familiar rich flavor, while mozzarella and Parmesan can add extra melt and a savory finish. Hash browns make each slice heartier, but the eggs and sausage still hold together without them.
Why This Breakfast Casserole Works
Sautéing the onion and bell pepper first softens them and removes some of their moisture before they meet the eggs. Cooked, drained sausage adds flavor without making the filling greasy. A brief rest after baking helps the slices hold their shape, which makes serving much easier.
Ingredient Notes
Eggs and milk: Six eggs create the custardy base. One cup of whole milk keeps it tender; use three quarters of a cup if you prefer a firmer slice. Whisk thoroughly so every portion bakes evenly.
Breakfast sausage and vegetables: Use fully cooked, crumbled sausage. Bell peppers and onion bring sweetness and color, while spinach or kale adds a little green. If starting with raw sausage, brown it completely in a skillet and drain it before assembly.
Potatoes and cheese: A cup of shredded hash browns makes the casserole more substantial. Cheddar is the main cheese; mozzarella and Parmesan are optional. Keep a small handful of cheese aside for the golden top. The ingredient photo also shows butter or oil for greasing the dish and garlic powder, which you may add as an optional seasoning.
How to Make Loaded Cheesy Breakfast Casserole
1. Prepare the dish and filling
Heat the oven to 350°F (175°C) and grease a 9-by-13-inch baking dish. In a lightly oiled skillet, soften the diced onion and bell peppers for about 3 to 4 minutes. If your sausage is raw, cook it separately until fully done, then drain it well.
2. Mix and assemble
Whisk the eggs with the milk, salt, black pepper and optional paprika. Stir in the sausage, softened vegetables, hash browns and chopped greens. Fold in the cheddar and any optional mozzarella or Parmesan. Pour the mixture into the prepared dish and scatter the reserved cheese across the surface.
3. Bake and rest
Bake for 40 to 45 minutes. The edges should be lightly golden and the center should look set rather than liquid; a knife inserted near the middle should come out clean. Let the casserole stand for 5 to 10 minutes before cutting. Finish with sliced green onions, and offer hot sauce at the table if you like heat.
Variations & Tips
Change the protein: Replace the cooked sausage with diced cooked ham or crisp bacon. Keep the amount close to one cup so the egg mixture remains balanced.
Add a little heat: Stir in finely chopped jalapeño or serve with hot sauce. For a smoky flavor, add the optional paprika or a small pinch of garlic powder.
Keep the texture right: Drain cooked sausage, avoid adding wet vegetables straight from washing, and do not overfill the baking dish. A slightly shorter rest gives softer spoonable portions; a longer rest gives neater squares.
Prepare ahead: Cook the sausage and vegetables ahead of time and keep them chilled. Assemble the casserole shortly before baking, or cover the assembled dish and refrigerate it overnight. If it goes into the oven cold, allow a little extra time and judge doneness by the center.
Serving and Leftovers
Serve warm with fresh fruit, toast or a crisp green salad. Leftover slices can be covered and refrigerated, then gently reheated until hot throughout. Individual portions also make a convenient breakfast for the following day.
Frequently Asked Questions
Can I leave out the hash browns?
Yes. The eggs still set and the sausage and vegetables remain the focus. The finished casserole will be a little lighter and less starchy.
Can I use a different cheese?
Yes. A good melting cheese can stand in for mozzarella, and you can keep all the cheese as cheddar if that is what you have. Avoid adding much more cheese than the recipe calls for, since the center may take longer to set.
How do I know it is done?
Look for a center that no longer jiggles loosely and a lightly browned surface. A knife inserted near the middle should come out clean. Resting the pan before slicing finishes the process.
Loaded Cheesy Breakfast Casserole Recipe Card
Loaded Cheesy Breakfast Casserole
Ingredients
Method
- Preheat the oven to 350°F (175°C). Grease a 9-by-13-inch baking dish.
- Cook the onion and bell peppers in a lightly oiled skillet for 3 to 4 minutes. If using raw sausage, brown it fully and drain before adding it to the casserole.
- Whisk the eggs, milk, salt, pepper, and optional paprika in a large bowl.
- Stir in the cooked sausage, vegetables, hash browns, and greens. Fold in the cheddar, mozzarella, and Parmesan, reserving a little cheese for the top.
- Pour into the prepared dish and sprinkle with the reserved cheese.
- Bake for 40 to 45 minutes, until the center is set and a knife inserted near the middle comes out clean.
- Rest for 5 to 10 minutes, then top with sliced green onions and serve.
