Melt the butter and oil in a large stockpot over medium heat. Cook onion and garlic for 5 minutes or until softened.
Add the mushroom. Cook for 5 minutes. Add the broth and simmer for 10 minutes.
Puree about half of the mushrooms with some of the broth and the cream cheese in a blender with the lid vented.
Add the mushroom puree back to the pot. Add the half and half, salt, and pepper. Turn heat to low.
Sprinkle the xanthan gum on top, if desired. Stir until dissolved. The soup will continue to thicken as it cools.
Notes
Nutrition: This keto soup recipe has 10 servings. It makes approximately 10 cups. A serving is one cup. There are 6.2 NET carbs per serving.Storage: Store the soup in the refrigerator for up to 4-5 days. Freeze for longer storage.