What’s better than a hearty, cheesy dish of mac and cheese for dinner? Turning the leftovers into an even more incredible breakfast the next morning. If you’ve got a container of cold, baked macaroni and cheese in your fridge, you are just a few simple steps away from the ultimate breakfast casserole.
Forget a sad, microwaved bowl of leftovers. We’re talking about a warm, savory, one-pan wonder where creamy pasta meets fluffy eggs, savory breakfast sausage, and a golden, bubbly cheese topping. It’s the kind of breakfast that makes getting out of bed on a weekend morning completely worth it.
In my experience, this is one of the best “repurpose” recipes ever. It’s unbelievably easy, and this step-by-step guide will walk you through every baby step to ensure it comes out perfectly. Let’s transform those delicious leftovers into a breakfast masterpiece.Turn last night’s dinner into the ultimate breakfast! This easy leftover mac and cheese breakfast casserole recipe is cheesy, savory, and packed with flavor. Ready in minutes!
Why This Breakfast Casserole is a Game-Changer
- Fights Food Waste: It gives a glorious second life to one of the most common leftovers, making your food (and money) go further.
- Incredibly Easy: This is a “mix, dump, and bake” style recipe. Minimal effort for maximum flavor.
- Perfect for Weekends & Holidays: It feeds a crowd and is the perfect hearty start for a lazy Saturday or a busy holiday morning.
- Completely Customizable: You can add whatever breakfast meats, veggies, or cheeses you have on hand.
Key Ingredients You’ll Need.
The beauty of this recipe is its flexibility, but here are the core components to get you started.
- Leftover Baked Mac and Cheese: You’ll need about 3-4 cups, cold from the fridge. Don’t worry if it’s a solid block; we’ll break it up.
- Large Eggs: 6 large eggs will create the savory custard that holds the casserole together.
- Milk: 1 cup of whole milk makes the egg custard rich and tender. You can also use half-and-half for extra richness.
- Breakfast Sausage: 1/2 pound of your favorite breakfast sausage (pork, chicken, or turkey). You can also use cooked, crumbled bacon.
- Shredded Cheese: 1 cup of shredded sharp cheddar or Monterey Jack cheese for that extra gooey, golden-brown top.
- Seasoning: Salt, black pepper, and maybe a pinch of smoked paprika or garlic powder.
How to Make the Casserole (Step-by-Step)
Let’s walk through this process one simple step at a time.
Step 1: Preheat Your Oven and Prep the Dish
- Get the Oven Ready: Preheat your oven to 375°F (190°C).
- Grease Your Dish: Lightly grease a 9×13 inch ceramic or glass baking dish with butter or non-stick cooking spray. This will prevent the casserole from sticking and make cleanup much easier.
Step 2: Cook Your Breakfast Meat.
- Heat a Skillet: Place a non-stick skillet over medium-high heat.
- Cook the Sausage: Add the breakfast sausage to the skillet. Use a spatula to break it up into small crumbles as it cooks.
- Brown It: Cook for about 5-7 minutes, until the sausage is fully browned and cooked through.
- Drain the Fat: Remove the skillet from the heat and use a slotted spoon to transfer the cooked sausage to a paper towel-lined plate to drain off any excess grease.
Step 3: Prepare the Egg Mixture.
- Get a Big Bowl: In a large mixing bowl, crack all 6 eggs.
- Add Milk and Seasoning: Pour in the 1 cup of milk. Add 1/2 teaspoon of salt, 1/4 teaspoon of black pepper, and a pinch of paprika if you’re using it.
- Whisk It Good: Use a whisk to beat the mixture thoroughly until the eggs and milk are completely combined and slightly frothy.
Pouring the egg custard mixture over the layers of the leftover mac and cheese breakfast casserole before baking.
Step 4: Assemble the Casserole.
This is where it all comes together!
- Layer the Mac and Cheese: Take your cold leftover mac and cheese and break it up into bite-sized chunks. Spread these chunks evenly across the bottom of your prepared baking dish.
- Add the Sausage: Sprinkle the cooked and drained sausage crumbles evenly over the mac and cheese layer.
- Pour the Egg Mixture: Slowly and evenly pour the whisked egg mixture over the entire casserole, making sure it gets into all the nooks and crannies.
- Top with Cheese: Sprinkle the 1 cup of shredded cheese evenly all over the top.
Step 5: Bake to Golden Perfection.
- Into the Oven: Carefully place the baking dish into your preheated oven.
- Bake: Bake for 30 to 40 minutes. You’ll know it’s done when the center is set (it doesn’t jiggle when you gently shake the pan) and the cheese on top is melted, bubbly, and golden brown. According to the USDA’s food safety guidelines, egg dishes are safely cooked when they reach an internal temperature of 160°F (71°C).
Step 6: Rest and Serve.
- Let It Rest (This is Important!): Remove the casserole from the oven and let it rest on a wire rack for at least 10 minutes before slicing. This step is crucial because it allows the casserole to set, ensuring you get clean slices that don’t fall apart.
- Slice and Enjoy: Use a sharp knife or a flexible spatula to cut into squares and serve warm.
Customization Ideas & Variations.
Feel free to get creative and use what you have in your fridge!
- Veggie-Packed Version: Sauté some diced bell peppers, onions, and mushrooms with your sausage and add them to the casserole.
- Spicy Southwest Twist: Use chorizo instead of breakfast sausage, add a can of drained green chiles, and use a Pepper Jack cheese topping. Serve with salsa and sour cream.
- Bacon Lover’s Dream: Swap the sausage for a pound of cooked, crumbled crispy bacon.
For more ideas on repurposing dinner, check out our guide on.
Frequently Asked Questions (FAQ)
Can I assemble this the night before?
Yes! This is a perfect make-ahead breakfast. Assemble the entire casserole as directed (but don’t bake it), cover it tightly with plastic wrap or foil, and refrigerate it overnight. In the morning, remove it from the fridge while the oven preheats and add an extra 5-10 minutes to the baking time.
My leftover mac and cheese is really dry. What should I do?
No problem at all! The egg and milk custard will add a lot of moisture back into it. You can also add an extra 1/4 cup of milk to the egg mixture if you’re concerned it will be too dry.
How do I know when the casserole is fully cooked?
The best way to tell is that the center should be firm to the touch and not jiggle when you gently shake the pan. If you insert a knife into the center, it should come out clean with no wet egg mixture on it.
The Best Breakfast You’ll Make All Year?
This recipe is the ultimate proof that leftovers can be exciting. It’s a comforting, hearty, and unbelievably delicious way to start your day and ensure not a single noodle of that amazing mac and cheese goes to waste.
Give this a try next weekend. I have a feeling it will become a new family tradition!
What are your favorite things to add to a breakfast casserole? Let me know in the comments below!