Filling
Preheat the oven to 375ºF.
In a large dutch oven, melt the butter over medium heat. Add the mushrooms, red pepper, onion, and celery, and sprinkle with salt and pepper. Cook until the vegetables are tender, about 5 minutes.
Stir in the garlic and sage and cook until fragrant, about 1 more minute. Stir in the broth, whipping cream, bay leaves and bring to a simmer. Whisk in the glucomannan, if using.
Season with additional salt and pepper to taste and then stir in the chicken. Continue to cook until the chicken is cooked through, about 10 minutes. Remove the bay leaves.
Using a slotted spoon, transfer the filling to a 2 quart glass or ceramic baking dish, leaving behind about half of the cooking liquid. (Don’t toss it, it makes a wonderful soup!).

Biscuit Topping
In a large bowl, whisk together the almond flour, coconut flour, baking powder, garlic powder, and salt. Stir in half the grated cheese.
Add the eggs, sour cream, and butter and stir until well combined. Let sit a few minutes to thicken.

Drop the topping in small spoonfuls over the filling and sprinkle with the remaining cheese. Bake 20 to 25 minutes or until filling is bubbling and crust is browned and firm to the touch.
Let stand about 10 minutes before serving.