Preheat oven to 400 F, and grease or oil a 9X6X2 inch casserole dish.
In a medium saucepan over medium heat combine: 1 tbsp butter or ghee, ½ cup sour cream or mayo, 2 tbsp red pepper sauce, 3 tbsp pumpkin puree, ½ tsp ground mustard spice, ¼ tsp garlic powder, and Parmesan cheese. Melt all ingredients and mix together until combined. Turn heat off.
Place zucchini noodles in a bowl and press down on noodles with a paper towel to remove excess water from noodles.
Spread zucchini noodles over bottom of casserole dish.
Place chopped cooked chicken and chopped celery on top of zucchini noodles.
Pour or spoon the creamy buffalo sauce from the stove top, over the chicken and celery.
Sprinkle optional chopped red bell pepper over the top of casserole.
Bake at 400 F for 30 minutes. Remove from oven, and sprinkle with optional grated cheese.
Let cool until sauce has thickened again and cheese has melted.