Preheat oven to 350°F. Spray a 9x13-inch baking dish with cooking spray and set it aside.

Cook 1 pound pasta (rigatoni or penne) according to package directions until al dente. Drain and set aside.

If your chicken is not already cooked, cook it through, then chop into bite-sized pieces. If it is cooked, chop it into bite-sized pieces and set aside.

Cut the pint of grape tomatoes in half. Reserve some tomato halves for garnish and set the rest aside for the casserole.

In a large bowl, whisk together 2 cups marinara sauce, 1/4 cup heavy cream, 1 tablespoon balsamic vinegar, and 1/4 cup grated Parmesan until smooth and combined.

Add the drained pasta, chopped cooked chicken, 6 ounces cubed mozzarella, the tomato halves reserved for the casserole, and 1/4 cup chopped fresh basil to the sauce. Gently toss until everything is evenly coated.

Transfer the pasta mixture to the prepared 9x13-inch baking dish and spread into an even layer.

Arrange the 6 fresh mozzarella rounds on top of the casserole in an even pattern.

Bake uncovered for 25–30 minutes, until the casserole is heated through and the cheese on top is bubbly.

Remove from the oven and let rest for a few minutes. Garnish with the reserved grape tomato halves and 1 tablespoon chopped fresh basil before serving.