Preheat the oven to 450°F and lightly coat a large baking sheet with cooking spray.
In a shallow bowl, mix the breadcrumbs and grated Parmesan cheese. In a separate bowl, melt the butter.
Lightly brush each chicken piece with the melted butter, then dredge it in the breadcrumb and Parmesan mixture until evenly coated. Arrange the breaded chicken on the prepared baking sheet. Repeat this process with each chicken piece.
Lightly spray the tops of the breaded chicken with additional cooking spray, then bake for 25 minutes.
Remove the chicken from the oven, and spoon 1 tablespoon of marinara sauce over each piece. Sprinkle each with about 1 1/2 tablespoons of shredded mozzarella cheese.
Return the chicken to the oven and bake for an additional 5 minutes, or until the cheese is fully melted and bubbly.