Mix all ingredients in a blender until smooth. Taste and blend in honey, if desired.
To make ahead, blend all ingredients except the ice. Store in a covered container in the refrigerator for up to three days. Blend with ice and dust with extra cocoa, as desired, just before serving.
Notes
Makes 24 ounces - 2 (12-ounce) servings
Thickness will be different depending on using regular vs. Greek yogurt, as well as the amount of ice.