Put everything except xanthan gum into blender and blend well, until mixture is no longer grainy and is very smooth. Scrape sides often.
Slowly sprinkle in xanthan gum and blend a bit longer.
Refrigerate for at least 6 to 8 hours, or until completely hardened. Whip with hand beater, just until smooth. Use immediately or store in cool place. It will harden in the refrigerator. Any leftover cream will need to be rewhipped before using.