Finely dice the onion into 1/4-inch pieces and mince the garlic cloves. Measure out the tomato paste, Worcestershire sauce, Italian seasoning, salt, and red pepper flakes into small bowls for easy access during cooking. Bring a large pot of salted water to a boil and add the penne, cooking according to package directions until al dente. Reserve 1 cup of pasta water before draining and set the cooked pasta aside in the pot.

Heat a large skillet over medium-high heat and add the ground beef with the salt and Italian seasoning. Cook for 4-5 minutes, breaking it up with a spoon as it browns, then continue cooking for 3-5 more minutes until the meat is fully cooked through. Drain off excess grease, leaving about 1-2 tablespoons in the pan for flavor. Lower heat to medium, add the diced onions and minced garlic, and sauté for 3-4 minutes until the onions become translucent and fragrant.

Stir the tomato paste and Worcestershire sauce into the cooked beef and aromatics, stirring constantly for about 1 minute to toast the paste slightly and deepen its flavor. Add the diced tomatoes with their juices and the red pepper flakes, stirring well to combine. Simmer for 1-2 minutes to allow the flavors to meld together. I find that toasting the tomato paste this way adds a subtle complexity that really elevates the sauce.

Pour the heavy cream into the sauce and stir for about 30 seconds to incorporate, then immediately add the freshly shredded cheddar cheese in batches, stirring constantly until each addition melts completely before adding more. For the best melting, I always shred cheddar from a block rather than using pre-shredded cheese, which contains anti-caking agents that can make the sauce grainy. Continue stirring until the sauce is smooth, creamy, and the cheese is fully integrated.

Pour the cheesy beef sauce from the skillet into the pot with the cooked penne and stir gently but thoroughly to coat all the pasta. Add 2-4 tablespoons of the reserved pasta water, starting with 2 tablespoons and adding more as needed to reach your desired sauce consistency—the starch in the pasta water helps the sauce cling beautifully to each piece. Taste and adjust seasoning with additional salt or pepper as needed. Serve immediately while hot and creamy.