Preheat the oven to 375°F. Bring a large pot of well-salted water to a boil.
Heat the olive oil in a large skillet or Dutch oven over medium heat. Add the ground beef and Italian sausage. Season with the kosher salt and freshly ground black pepper.
Cook the meat, breaking it up with a spoon, until fully browned and cooked through, about 8–12 minutes. Let it develop good color for the best flavor.
Stir in the marinara sauce and simmer uncovered for 10–15 minutes, just until the sauce comes together. Taste and adjust seasoning if needed.
Meanwhile, cook the rigatoni until very al dente, about 2 minutes shy of package directions. Drain well.
Remove the sauce from the heat and stir in the Parmesan cheese until fully incorporated.
Add the cooked rigatoni to the sauce and toss until evenly coated. Fold in about two-thirds of the ricotta, mixing gently until the sauce is lightly creamy but still meat-forward.
If the skillet is oven-safe, the pasta can be baked directly in it. Otherwise, transfer the mixture to a lightly greased 9×13-inch baking dish. Spread into an even layer and dollop the remaining ricotta over the top.
Sprinkle the mozzarella evenly over the surface.
Cover loosely with foil and bake for 25–30 minutes, until hot and bubbling.
Remove the foil and bake uncovered for another 10 minutes, until the cheese is melted and lightly golden. Remove from the oven, top with fresh basil if desired, and serve.