Combine the blueberries, sweetener, and zest in a small saucepan.
Bring to a simmer over medium heat. Reduce to medium-low and simmer for 10 minutes.
Sprinkle the xanthan gum over the blueberries and mix in well. It will continue to thicken as it cools. Transfer to mason jars or other storage containers. Store in the refrigerator.
Nutrition: The nutrition facts are for 1/16th of the recipe. This is approximately one ounce. There are 3.4 net carbs per serving.Storage: This will keep 2-3 weeks in the fridge. You can freeze it for longer storage.Notes on Sweeteners: