Pre-heat oven to 400 degrees and line a baking sheet with foil. Spray with cooking spray and set aside.
In a medium bowl, mix together ground chicken, zucchini, salt, fennel and pepper. Scoop mixture out into small balls and line in single layer on baking sheet.
Bake meatballs for 20 minutes, turning once halfway through.
Serve meatballs over cooked rigatoni tossed with olive oil, salt and pepper to taste.