Preheat oven to 400 degrees F. Spray a 9x13 inch baking dish with cooking spray.
Place a large non-stick skillet over medium-high heat. Add the chicken and break it apart with a spoon. Add the salt and pepper. Cook for 8 to 10 minutes, until chicken is cooked through. Stir occasionally and break down the chicken into small chunks.
Reduce the heat to low. Add the garlic to the chicken. Cook 1 minute stirring often. Add the pasta sauce. Cook 3 minutes, stirring occasionally.
As the chicken cooks, cut the zucchini in half, lengthwise. Use a spoon to scoop the seeds and center out of each zucchini half, leaving a 1/4 inch thick zucchini boat.
Place the zucchini in the baking dish cut-side up.
Spoon the chicken mixture into the zucchini boats. Press the mixture down into the zucchini using the back of the spoon.
Sprinkle the zucchini evenly with the parmesan, then the mozzarella cheese.
Cover the baking dish with foil. Bake for 35 minutes.