Before You Begin Shred the cheddar from a block and set aside. Measure out all ingredients and leave the cream cheese at room temperature to soften. Start heating a large pot of salted water for the pasta.
Cook the Beef Season the ground beef with salt and pepper. Heat a large deep skillet over medium-high heat and add the beef. Cook and crumble for about 4 minutes, then add the diced onion and continue cooking for another 5 minutes until the onion is softened and the beef is fully cooked through. Drain excess grease from the pan.
Add Garlic Add the minced garlic and cook, stirring, for 1 minute until fragrant.
Build the Seasoning Add the hot sauce, Worcestershire sauce, Italian seasoning, mustard powder, red pepper flakes, and flour. Stir to coat the beef and cook for 1 to 2 minutes.
Deglaze and Simmer Add the beef broth and use a silicone spatula to scrape up any browned bits from the bottom of the pan. Stir in the tomato sauce, tomato paste, and softened cream cheese. Let the sauce simmer over medium heat while you cook the pasta shells according to package directions, about 7 to 8 minutes, until al dente.
Finish the Sauce Reduce the heat to low and stir in the half and half. Remove the pan from the heat completely. Gradually stir in the shredded cheddar in small amounts, letting each addition melt before adding more, until the sauce is smooth and glossy.
Combine Drain the pasta and add it to the skillet. Fold everything together until the shells are evenly coated in the sauce. Taste and adjust seasoning as needed.
Serve Garnish with fresh parsley and freshly grated Parmesan. Serve immediately with garlic bread on the side.