Spray counter lightly with non-stick cooking spray. Flatten each roll into a 5-inch circle. Place 1 teaspoon marinara sauce in the center of each circle. Top with 1 meatball and a piece of string cheese cut in half. Place a piece of cheese on two sides of the meatball. Pull dough up around filling to completely enclose and pinch to seal.
Place one seam side down in each cup of a sprayed 12 cup muffin tin. Brush each one with butter and sprinkle with Parmesan cheese and Italian seasoning.
Cover with sprayed plastic wrap and let rise 30-45 minutes.
Remove wrap and bake at 350°F 20-25 minutes. Serve warm with warm marinara sauce, if desired.