In a large bowl whisk together sugar, milk powder, and xanthan gum.
Add milk and root beer syrup. Mix very well.
Add cream and mix well again.
Place mixture in a sealed contained and refridgerate for 12+ hours.
Churn according to your ice cream maker's instructions.
Split the ice cream into two containers, each ~1L in size. You now have Root Beer ice cream. To make it root beer float ice cream, make your favourite vanilla ice cream, and layer on top of your root beer ice cream!