01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with cooking spray or a small amount of oil.
02 - Bring a large pot of salted water to a rolling boil. Add rigatoni and cook until just al dente, about 2 minutes less than package directions. Drain thoroughly and set aside.
03 - Heat a large skillet over medium heat. Add ground beef and cook, breaking apart with a wooden spoon, until browned and fully cooked through, about 6-8 minutes. Drain excess fat if necessary.
04 - Add diced onion to the beef and cook for 3-4 minutes until softened and translucent. Stir in minced garlic and cook for 1 minute until fragrant.
05 - Pour in marinara sauce and crushed tomatoes. Add oregano, basil, red pepper flakes, salt, and pepper. Reduce heat to low and simmer for 8-10 minutes, stirring occasionally to meld flavors.
06 - In a large mixing bowl, combine cooked rigatoni, meat sauce, and ricotta cheese. Gently fold together until pasta is evenly coated.
07 - Spread half the pasta mixture in the prepared baking dish. Sprinkle with half the mozzarella and Parmesan. Layer remaining pasta on top, then finish with remaining cheeses.
08 - Cover baking dish loosely with aluminum foil. Bake for 20 minutes to heat through and meld flavors.
09 - Remove foil and continue baking for 10-15 minutes until cheese is bubbly and golden brown on top.
10 - Let casserole rest for 5 minutes before serving to set. Garnish with fresh parsley or basil if desired.