Preheat the oven to 350°F (175°C). Grease a 9×13 inch casserole dish and set aside.
Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente, about 7-8 minutes. Drain and set aside.
In a large skillet over medium-high heat, add the ground beef, diced onion, and minced garlic. Cook, breaking up the beef with a spoon, until the beef is browned and the onion is softened, about 6-8 minutes. Drain excess fat if necessary. Season with salt and black pepper. Remove from heat and set aside.
In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes until lightly golden and bubbling.
Gradually whisk in the milk, ensuring no lumps form. Continue to cook, whisking frequently, until the sauce thickens and coats the back of a spoon, about 5-7 minutes.
Remove the sauce from heat and stir in the sharp cheddar cheese, mozzarella cheese, Parmesan cheese, smoked paprika, dry mustard powder, and cayenne pepper until the cheese is fully melted and the sauce is smooth.
Add the cooked macaroni and browned ground beef mixture to the cheese sauce. Stir gently to combine everything evenly.
Pour the mac and cheese mixture into the prepared casserole dish and spread it out evenly.
Sprinkle the breadcrumbs evenly over the top of the casserole.
Bake in the preheated oven for 20-25 minutes, or until the top is golden brown and the casserole is bubbly.
Remove from the oven and let cool for 5 minutes before serving.