In a small saucepan over medium heat, mix the water and granulated erythritol (or similar sweetener). Bring to a low boil.
Stir in butter and vanilla extracts. Reduce heat to low.
In a small bowl or cup, mix the xantham gum with a tablespoon of hot water and stir with a fork to remove as many clumps as possible. It will thicken up quickly and not dissolve completely.
Add the xantham gum mixture to the saucepan, stirring continually. Raise the heat to medium and bring the mix back to a low boil. Cook for one minute until the mixture starts to thicken. Remove from heat.
Pour the corn syrup thru a sieve, pressing the corn syrup thru while leaving the xantham gum solids in the sieve.
Allow to cool slightly before using in your recipe.
Recipe updated to include additional vanilla extract and salt to improve flavor.