Step 1

For the meatballs: Preheat the oven to 350 degrees F. Coat a baking sheet with nonstick cooking spray.

Step 2

Mix together the chicken, pumpkin, Parmesan, onion, parsley, salt, pepper and garlic in a large bowl. Cover and refrigerate 20 minutes.

Step 3

Shape the mixture into balls using a tablespoon and place on the prepared baking sheet. Bake until cooked through, 12 to 15 minutes. Increase the oven temperature to 400 degrees F and spray a 9-by-13-inch baking dish with cooking spray.

Step 4

For the casserole: Meanwhile, bring a large pot of water to a boil. Season generously with salt. Add the pasta and cook 3 minutes less than the package instructions. Reserve 1/3 cup pasta water and drain.

Step 5

Toss the pasta with the marinara sauce and pasta water in a large bowl. Transfer to the greased baking dish. Nestle the meatballs into the pasta. Top with the mozzarella and sprinkle with the Parmesan.

Step 6

Bake until the cheese is melted and bubbly, about 20 minutes. Let stand for 5 minutes. Serve with grated Parmesan.