Bring a large pot of generously salted water to a boil. Cook the pasta according to the package directions until just al dente, reserve about ½ cup of pasta water, and drain.

Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the ground beef and cook for 5–7 minutes, breaking it into small pieces, until browned; drain excess fat if needed.

Add the diced onion and cook for 3–4 minutes until softened. Stir in the garlic, Italian seasoning, paprika, and optional red pepper flakes, then cook for about 30 seconds.

Sprinkle the flour over the beef mixture and stir for 1 minute. Gradually pour in the beef broth while stirring, then add the tomato sauce, kosher salt, and black pepper.

Bring the sauce to a gentle simmer and cook for 5–8 minutes, stirring occasionally, until it is slightly thickened. Reduce the heat to low before adding the cream.

Stir in the heavy cream without allowing the sauce to boil vigorously. Add the cooked pasta and toss until coated, then stir in the cheddar cheese until melted.

Add a splash of reserved pasta water if the sauce is too thick. Taste and adjust the seasoning, garnish with parsley or Parmesan, and serve hot.