Cook the Pasta:
Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Drain and set aside.
Prepare the Ground Beef:
In a large skillet, heat the olive oil over medium-high heat. Add the chopped onion and cook until softened, about 3-4 minutes.
Add the garlic and cook for another minute until fragrant.
Add the ground beef to the skillet, breaking it apart with a wooden spoon. Cook until browned and no longer pink. Drain any excess fat.
Combine the Ingredients:
Add the tomato sauce, diced tomatoes (with their juice), Italian seasoning, red pepper flakes, salt, and pepper to the skillet. Stir to combine.
Reduce the heat to low and let the mixture simmer for about 10 minutes, allowing the flavors to meld.
Make the Cheese Sauce:
In a medium saucepan, heat the heavy cream over medium heat until it begins to simmer.
Reduce the heat to low and gradually add the cheddar cheese, mozzarella cheese, and Parmesan cheese, stirring constantly until the cheese is fully melted and the sauce is smooth.
Combine Everything:
Add the cooked pasta to the skillet with the ground beef mixture, stirring to combine.
Pour the cheese sauce over the pasta and beef mixture, stirring until everything is well coated and the sauce is evenly distributed.
Serve:
Serve the cheesy ground beef pasta hot, garnished with chopped fresh parsley if desired.