Build the pizza: Preheat the oven according to pizza package directions. In a medium-size bowl, toss the shredded chicken with the buffalo sauce. Top the frozen pizza with the chicken and sprinkle the cheese over everything. Place the pizza into the oven and cook according to package directions.
Make the garnish: Using a vegetable peeler, make celery ribbons by running the peeler, longways, down the side of the celery rib. Place them into ice water until you’re ready to use. Chop the celery leaves and reserve for garnish.