Cook the Pasta:

• Bring a large pot of salted water to a boil. Add the rigatoni and cook according to package instructions until al dente. Drain and set aside.

Cook the Beef:

• In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Add the chopped onions and cook until soft, about 3-4 minutes.
• Add the ground beef to the pan. Break it up with a spoon and cook until browned, about 5-7 minutes.
• Stir in the minced garlic, salt, and pepper. Cook for an additional minute until fragrant. Remove from heat and set aside.

Make the Creamy Garlic Butter Sauce:

• In the same skillet, melt 4 tablespoons of butter over medium heat. Add the minced garlic and cook for about 1-2 minutes until fragrant.
• Pour in the heavy cream and whole milk. Bring to a simmer and cook for 3-5 minutes, allowing the sauce to thicken slightly.
• Stir in the shredded mozzarella and grated Parmesan. Continue to cook until the cheeses melt and the sauce is smooth and creamy.
• Season with salt, pepper, Italian seasoning, and red pepper flakes (if using). Adjust the seasoning to taste.

Combine the Pasta and Beef:

• Add the cooked rigatoni to the creamy sauce and toss until well coated.
• Gently fold in the cooked beef mixture. Continue to stir until everything is combined and heated through.

Serve:

• Plate the creamy rigatoni with beef and sprinkle with fresh chopped parsley for garnish.
• Serve immediately while hot, with extra Parmesan cheese on the side if desired.