Step 1: Preheat your oven to 375°F (190°C) and lightly grease a 9x13 inch baking dish.
Step 2: Bring a large pot of salted water to a boil and cook the rigatoni for 2 minutes less than the package directions for al dente.
Step 3: While the pasta cooks, brown the ground beef and chopped onion in a large skillet over medium-high heat until cooked through. Drain any excess fat.
Step 4: Stir in the minced garlic, salt, pepper, garlic powder, paprika, Italian seasoning, and red pepper flakes. Cook for 1 minute until fragrant.
Step 5: Add the marinara sauce and heavy cream to the skillet. Simmer on low for 5 minutes.
Step 6: Drain the pasta and toss it into the meat sauce until thoroughly coated.
Step 7: Pour half of the pasta mixture into the prepared baking dish. Top with dollops of ricotta cheese and half of the mozzarella.
Step 8: Layer the remaining pasta on top and sprinkle with the rest of the mozzarella and Parmesan.
Step 9: Bake for 20-25 minutes until the cheese is melted and bubbly. Garnish with dried parsley before serving.