Place the ground beef and chopped onions in a large Dutch oven or soup pot and cook over medium-high heat until the beef is fully browned, about 7 to 10 minutes, breaking it apart with a spoon as it cooks. Drain any extra fat.
Mix in the tomato paste, garlic powder, paprika, and Italian seasoning until everything is well combined.
Pour in the beef broth, heavy cream, and Worcestershire sauce, then raise the heat to bring the mixture to a boil.
Once boiling, add the uncooked pasta shells to the pot.
Lower the heat to maintain a gentle simmer and cook uncovered for about 12 to 13 minutes, stirring every few minutes until the pasta is tender and most of the liquid has evaporated.
Remove the pot from heat and stir in the cubed Velveeta cheese until it melts completely.
Season with salt and pepper to your liking, and let it sit for a few minutes so the sauce thickens up before serving, or enjoy immediately.
