📝 Step-by-Step Instructions
Step 1: Prep the Pasta and Meatballs
Preheat your oven to $375^{\circ}\text{F}$ ($190^{\circ}\text{C}$). Lightly grease a 9×13-inch casserole dish.
Cook the elbow macaroni according to package directions, but cook it for about 1 minute less than required (al dente). Drain the pasta and set it aside.
If using uncooked meatballs, cook them separately (by searing or baking) until they are mostly cooked through.
Step 2: Make the Velvety Cheese Sauce
In a large saucepan or pot, melt the butter over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly (this is the roux).
Slowly whisk in the milk until the mixture is smooth. Bring the sauce to a gentle simmer, whisking frequently. It should thicken slightly after 5-8 minutes.
Remove the saucepan from the heat. Stir in the Cheddar and Gruyère/Monterey Jack cheese, stirring until the cheese is fully melted and the sauce is smooth and creamy.
Stir in the salt, pepper, and nutmeg. Taste and adjust seasoning as needed.
Step 3: Assemble the Casserole
Add the cooked macaroni and the meatballs into the cheese sauce. Gently stir until the pasta and meatballs are completely coated in the rich sauce.
Pour the mixture into the prepared 9×13-inch casserole dish, spreading it into an even layer. Ensure the meatballs are distributed across the top (as pictured).
Step 4: Bake to Perfection
Sprinkle the reserved 1 cup of Mozzarella cheese evenly over the top of the casserole.
Bake for 25 to 30 minutes, or until the sauce is bubbling hot throughout, and the top is melted, golden, and slightly crispy.
If the cheese is not browning enough, place the dish under the broiler for the last 1-2 minutes, watching very closely to prevent burning.
Step 5: Garnish and Serve
Remove the casserole from the oven and let it rest for 5-10 minutes before serving. This allows the sauce to set slightly.
Garnish generously with fresh chopped parsley, if desired.
Serve hot!
💡 Pro Tips for Casserole Success
Cooked Pasta is Key: Undercooking the pasta slightly (al dente) prevents it from turning mushy as it continues to cook in the sauce while baking.
Cheese Quality: Use block cheese that you shred yourself, as pre-shredded cheese contains anti-caking agents that can prevent a smooth melt.
Freezing Option: You can assemble the casserole (up to Step 3, without the final mozzarella topping), cover it tightly, and freeze for up to 3 months. Thaw overnight in the fridge before baking.
