Preheat the oven to 425° F. Place the chicken wings on a wire rack set on a sheet pan. Bake for 1 hour.
While the wings cook, saute the mushrooms in a large dutch oven over medium heat until they have released their liquid, about 20 minutes. Remove the mushrooms from the pan and set aside.
Transfer the wings to the Dutch oven and add the garlic. Stir to combine. Add the chicken broth, and bring to a boil over high. Reduce the heat to low, and simmer until it reduces by half, about 1 hour.
Pour the liquid through a mesh strainer and discard the solids. Return the liquid and the mushrooms to the pan.
Add the butter and whipping cream to the pan over low heat.
When the butter is melted stir in the xanthan gum and season to taste with salt and pepper. Simmer for 5 minutes, until thickened.
Please note that nutritional information is off because you are actually discarding the chicken wings and not eating the chicken.