Step 1: Prepare the Macaroni and Cheese

Cook the Macaroni: Bring a large pot of salted water to a boil. Cook the macaroni according to package instructions until al dente. Drain and set aside.

Make the Cheese Sauce:
In a medium saucepan, melt butter over medium heat.
Stir in the flour and cook, stirring constantly, for about 1 minute to make a roux.
Gradually whisk in the milk, stirring constantly until the sauce thickens, about 3-5 minutes.
Remove from heat and stir in shredded cheddar cheese, salt, and pepper until melted and smooth.

Combine: Pour the cheese sauce over the cooked macaroni and stir to coat. Set aside.

Step 2: Prepare the Beef Layer

Cook the Beef:
In a large skillet, cook the ground beef over medium heat until browned, breaking it into small pieces.
Add the chopped onion and garlic, and cook for another 3-5 minutes until the onion is soft and translucent.

Season: Add salt, pepper, and Italian seasoning, stirring well to combine.

Add Marinara: Stir in the marinara sauce and cook for a few minutes until heated through. Remove from heat.

Step 3: Assemble the Casserole

Layer the Dish:
Preheat your oven to 375°F (190°C).
In a greased 9×13-inch baking dish, spread the beef mixture evenly over the bottom.
Top with the macaroni and cheese layer, spreading evenly.

Add Cheese Topping: Sprinkle the shredded mozzarella cheese over the top.

Step 4: Bake

Place the casserole in the preheated oven and bake for 20-25 minutes, until the cheese is bubbly and golden on top.

Step 5: Garnish and Serve

Garnish: Sprinkle chopped parsley over the casserole for a pop of color. 

Serve: Let the casserole sit for about 5 minutes before serving.

Tips

Make It Spicy: Add a pinch of red pepper flakes to the beef mixture for a little heat! 
Add Vegetables: Mix in diced bell peppers, mushrooms, or spinach for added nutrition. 
Make-Ahead: Assemble the casserole, cover, and refrigerate for up to 24 hours before baking. 
Enjoy your hearty, cheesy, and comforting macaroni and beef casserole!