Step 1: Bring a large pot of salted water to a boil. Cook the penne until just al dente (9 to 11 minutes). Drain well and set aside.

Step 2: In a large skillet, melt the butter over medium heat. Add the ground beef and break it apart. Cook, stirring occasionally, until browned, about 7–8 minutes.

Step 3: Add the chopped onion to the skillet. Cook for 3 minutes until soft, then add the minced garlic. Stir for 1 minute until fragrant.

Step 4: Stir in Italian seasoning and red pepper flakes (optional). Mix well to coat the beef and aromatics.

Step 5: Pour in heavy cream and beef broth. Scrape the skillet bottom to loosen browned bits. Simmer for 2–3 minutes until the sauce thickens slightly.

Step 6: Gradually add mozzarella and Parmesan cheese, stirring constantly until melted and smooth. If the sauce is too thick, add a splash of reserved pasta water to loosen.

Step 7: Add the cooked penne to the skillet. Toss gently to coat pasta evenly with sauce.

Step 8: Taste and adjust salt and pepper as needed, remembering the cheeses add saltiness.

Step 9: Remove from heat and let the pasta rest for a minute to let flavors meld.

Step 10: Serve hot, garnished with chopped parsley for freshness and color.