In a large pot, bring water to a boil and add the cauliflower florets. Boil for about 5-7 minutes until tender but not mushy. Drain and set aside.
In a large mixing bowl, combine the shredded chicken, buffalo sauce, softened cream cheese, half of the shredded cheddar cheese, ranch dressing, diced celery, and sliced green onions. Mix until well combined.
Gently fold in the cooked cauliflower until the mixture is evenly distributed. Season with salt and pepper to taste.
Pour the mixture into a greased baking dish. Sprinkle the remaining cheddar cheese on top, followed by breadcrumbs for added crunch if desired.
Bake in the preheated oven for about 25-30 minutes, or until bubbly and the top is golden brown.
Once done, remove from the oven and allow to cool for a few minutes. Garnish with fresh parsley before serving.