Preheat the oven to 350 degrees F and lightly grease a 9x13 baking dish with cooking spray.
Bring a large pot of salted water to a boil. Add the pasta shells and cook until tender, about 10 to 12 minutes, stirring occasionally. Drain and transfer shells to the prepared baking dish, then stir in the butter until melted.
Next, add the ground beef, diced red onion, and minced garlic to a frying pan and cook over medium-high heat until beef is browned, about 7 to 10 minutes. Break the beef up into small chunks as it cooks.
In the meantime, add cubed Velveeta and milk to a medium saucepan and cook over medium heat until cheese is melted, stirring occasionally, about 8 to 10 minutes. Then turn heat to low and stir in ketchup, Worcestershire sauce, paprika, salt, and cooked ground beef with onions and garlic.
Pour the cheese sauce over the pasta shells in the baking dish. Stir to combine until the shells are thoroughly coated in cheese sauce. Then bake in the oven for 10 minutes to help the sauce soak into the pasta.
Serve hot or store in the fridge for up to 5 days.
Notes
Timing - If you start cooking the ground beef and cheese sauce while the pasta boils, you can time this recipe to have everything ready to combine at the same time. Just make sure the ground beef finishes cooking before the cheese is fully melted so that you’re not waiting around to add the beef to the cheese sauce.Servings - One pound each of pasta shells, ground beef, and Velveeta is enough to make about 6 servings of cheeseburger mac and cheese – which easily fills an entire 9×13 baking dish. This is a great way to make lunches for the week, feed the whole family, or serve as a side at a summer cookout.Storing and reheating - Store in the fridge for up to 5 days. To reheat single servings, microwave for about 1 to 2 minutes, stirring halfway through.Other Fillings - Just like cheeseburger toppings, you can add other fillings to this mac n cheese. Cooked bacon is always a winner. But you can get creative such as cooking some pickle relish in with the beef, or adding other seasonings to the cheese sauce.