The night before (or at least 3 hours before): Pour 3/4 cup of the coconut milk into an ice cube tray. Reserve the remaining coconut milk in the refrigerator.
Remove the pits from the dates. When the ice cubes are set, place the reserved coconut milk, cocoa powder, dates, and vanilla extract in a blender. Blend until smooth. Add the coconut milk ice cubes and blend again until smooth.