In a medium saucepan over medium heat combine butter, brown Swerve and granulated Swerve. Stir together until butter is completely melted (I cut my butter into cubes so it melts faster )
Bring to a low boil over medium heat. Allow to simmer 3-5 minutes or until the mixture slightly darkens and begins to smell like caramel. Be careful not to burn. DO NOT allow to simmer more than 5 minutes
Remove from the heat. Carefully add the milk (it will bubble slightly) Stir to combine the milk
Very gradually sprinkle in the xanthan gum in small amounts whisking while you add. Once the xanthan gum is completely added whisk vigorously for about 20 seconds to make sure all the xanthan gum is fully dissolved
Whisk in the salt until combined. Return back to the heat. Bring back up to a low boil over medium heat. Allow to simmer about 1 minutes or until everything is creamy and smooth
Remove from the heat. Add the water and whisk until fully combined and smooth. Allow to cool in the pan about 15 minutes. Pour into and airtight container. Allow to cool completely. Store in the refrigerator up to 1 week. If the sauce thickens after refrigerating remove the lid and microwave on a high a few seconds or until it is able to be poured.