Follow these simple steps to create the Irresistible Mac and Cheese Meatloaf Casserole:

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Cook Pasta: Boil the elbow macaroni according to package directions. Drain and set aside.
3. Prepare Meatloaf Mixture: In a large bowl, combine ground beef, ground pork, breadcrumbs, chopped onion, minced garlic, eggs, Worcestershire sauce, salt, and pepper. Mix thoroughly until well incorporated.
4. Shape Meatloaf: Form the meat mixture into a loaf shape and place it in a baking dish or casserole dish.
5. Bake Meatloaf: Bake in the preheated oven for about 30-35 minutes, or until the internal temperature reaches 160°F (71°C).
6. Make Cheese Sauce: Meanwhile, in a saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes.
7. Add Milk: Gradually whisk in the milk, stirring continuously until the mixture thickens.
8. Add Cheese: Remove from heat and stir in mustard powder, paprika, and shredded cheddar cheese until melted and smooth.
9. Combine: In a large bowl, mix the cooked elbow macaroni with the cheese sauce until well coated.
10. Layer the Casserole: Once the meatloaf is done baking, spread the mac and cheese mixture evenly over the top.
11. Add Extra Cheese: Sprinkle additional shredded cheese on top of the mac and cheese layer.
12. Finish Baking: Return the dish to the oven and bake for an additional 15-20 minutes until the cheese on top is melted and bubbly.
13. Cool and Serve: Remove from the oven and allow to cool for about 10 minutes before slicing and serving.