Preheat the oven to 200 degrees Celsius. Place an ovenproof skillet pan over medium heat, then add in the butter and avocado oil. Once the butter melts, add in the onions, carrots, and celery and sauté for six to eight minutes until the veggies become soft. Next, add in the chicken alongside some sprinkles of salt and pepper to taste then cook for a few minutes until the chicken is half cooked.
Next, add in the chicken broth, heavy cream, and xanthan gum then simmer for a few minutes until the sauce thickens. In the meantime, make the biscuit dough. Using a large mixing bowl, add in almond flour, garlic powder, salt, baking powder, egg, cheese, and butter then mix properly to combine.
Use a cookie scoop to scoop the dough over the filling in the saucepan, press down to flatten then place the skillet pan into the preheated oven. Bake the pie for about twenty minutes until it is cooked through then serve.