Preheat your oven to 350°F (175°C) with a rack in the center.

In a large pot, boil salted water and cook the rigatoni until al dente for about 9-11 minutes.

In a Dutch oven, heat oil and sauté ground sausage and beef for about 10 minutes until browned.

Add diced onion and minced garlic, and sauté until the onion is translucent, about 3-4 minutes.

Stir in marinara sauce, crushed tomatoes, kosher salt, Italian seasoning, and butter, cooking for about 3 minutes.

Mix the drained rigatoni into the sauce in the Dutch oven, folding gently until well coated.

Transfer to a 9 x 13 inch baking dish, spreading evenly, then sprinkle mozzarella cheese on top.

Cover with aluminum foil and bake for 25 minutes.

Remove foil and bake uncovered for an additional 10-15 minutes until cheese is golden brown and bubbly.

Let it rest for 5-10 minutes, then sprinkle with minced parsley before serving.