Combine cream, sweetener, vodka, vanilla extract, xanthan gum, and salt in a wide-mouth pint-sized jar. Blend cream mixture with an immersion blender in an up-and-down motion until cream has thickened and soft peaks have formed, 60 to 75 seconds. Cover jar and place in the freezer for 3 to 4 hours, stirring every 30 to 40 minutes.