Prepare cauliflower crusts according to recipe directions. Combine the shredded chicken with the buffalo sauce and stir to coat evenly.
Spread an even layer of cheese on both crusts. Divide the buffalo chicken between the two pizzas, making sure to spread evenly. Top with blue cheese (if using) and bake at 425º F for 5-10 minutes, until the cheese is melted and the chicken is warmed through.
Remove the pizzas from the oven, and drizzle with lots of ranch and additional buffalo sauce. Sprinkle celery slices over the top, cut into slices and serve!