In a medium saucepan over medium-high heat, whisk together the cream, milk, sweetener, and cocoa powder.
Bring to a boil and cook for 1 minute, stirring frequently.
Remove from heat and stir in vanilla.
Sprinkle the surface with xanthan gum and whisk briskly to combine. Let the mixture cool at least 10 minutes, then pour into popsicle molds.
Freeze 1 hour, then insert sticks two-thirds of the way. Return to freezer and freeze until solid, at least 5 hours or overnight.To unmold: run warm water over the outside of the mold for 5β10 seconds, then gently tug the stick to release.