In a medium saucepan over medium-low, heat the cake mix until it reaches 160°F. Stir continuously to prevent burning. Add the xanthan gum, whisking to combine into cake mix.
Combine the heavy cream and milk, add about ½ cup to the saucepan, whisking the dry ingredients until dissolved into the liquid. Add the remaining milk and cream. Cook another two minutes or so, ensuring the dry ingredient as dissolved. Remove from heat and whisk in the vanilla extract.
Strain the mixture through a sieve into the Ninja Creami pint container. Cool on the counter for about 20 minutes. Seal tightly and place in the freezer for 24 hours until frozen solid.
Remove frozen pint, for the first spin, press the ice cream button. Remove the outer bowl lid. If you want to add sprinkles, do so at this time. The ice cream will appear crumbly. Place it back in machine and press re-spin button. For a more soft-serve texture, you can spin for a third time, I recommend the mix-in setting. Serve immediately.