Preheat oven to 450 degrees. Lightly spray baking pan with cooking spray.
Slice the chicken breasts in half horizontally to make 6 cutlets, season both sides
In a shallow bowl combine breadcrumbs and cheese. In a small bowl combine butter and oil. Brush the butter and oil on both sides of the chicken, dredge the chicken in the bread crumb mixture and place on the baking pan. Lightly spray the top with cooking spray. Bake until golden brown on top, about 20 minutes. Turn the chicken over and bake until cooked through and golden, about 5 minutes.
Meanwhile in a large covered skillet, cook the marinara sauce over medium heat until heated through, 5 to 6 minutes. Place the baked chicken in the skillet and top each piece with 11/2T of the mozzarella. Cover the pan and cook until the cheese is melted, 3-4, minutes. Serve hot