Preheat the oven to 350º F.
In a large pot over medium heat, melt butter and sauté the onions, 1/2 cup of the celery, and the carrots until soft, but not brown. Season with salt and pepper.
Sprinkle the flour and stir until well mixed. Slowly add the stock. Bring to a boil, then lower heat and let simmer for 5–10 minutes until slightly thickened.
Add the 1/4 cup TRUFF Hot Sauce, chicken, and sour cream. Mix well.
Meanwhile, place pie crust flat on a parchment-lined baking tray, score with a fork, and brush with reserved 2 Tbsp of TRUFF Hot Sauce.
Bake in a preheated oven until the pie crust is set and crisp, about 15–20 minutes.
Cut into wedges to serve with the TRUFF-alo chicken mixture and garnish with the reserved raw chopped celery, crumbled blue cheese, and additional TRUFF Hot Sauce.