Preheat an oven to 350℉. Coat the inside of a 9x13 baking dish with cooking spray, set aside.
Nonstick cooking spray
In a large pot of salted water, cook the spaghetti according to the box directions, leaving slightly firm, or al dente. Drain and return the pot, then toss together with the butter and 1 cup of the marinara sauce until the noodles are completely coated.
1 pound dry spaghetti noodles, 4 tablespoons unsalted butter, 2 24-ounce jars marinara sauce, divided
While the spaghetti cooks, add the olive oil to a large skillet over medium high heat. Once the oil is heated through and begins to shimmer, add the diced onion and garlic. Sauté for 7 to 8 minutes until translucent. Add the ground beef and sausage to the pan, followed by the salt, pepper and Italian seasoning. Cook for 8 to 10 minutes until cooked through and no longer pink, using a spatula to break up the meat as it cooks. Drain away any excess cooking oil, then stir in the remaining marinara sauce.
2 tablespoons olive oil, 1 yellow onion, diced, 4 cloves garlic, minced, 1 pound lean ground beef, 8 ounces Italian sausage, 2 teaspoons kosher salt, ½ teaspoon black pepper, 2 tablespoons Italian seasoning
In a separate bowl, mix together the cream cheese, ricotta and Parmesan until combined.
8 ounces cream cheese, softened, 2 cups ricotta cheese, ¾ cup grated Parmesan cheese
Add the noodles to the bottom of the baking dish, then spread the cheese mixture evenly over the top, making sure to spread all the way to the edge of the pan. Top with meat sauce, then sprinkle with the shredded mozzarella and chopped parsley.
1 ½ cups shredded mozzarella cheese, ¼ cup parsley, chopped
Bake for 25 to 30 minutes until the cheese is completely melted and the sauce starts to bubble around the sides of the pan. Let sit for 10 to 15 minutes before serving.