Chop the dark chocolate into small pieces.
Pour the heavy cream into a pot and heat until just before boiling.
Add the chocolate to the warmed cream and stir until melted.
Add erythritol and stir well until fully dissolved.
Pour the mixture into a mold lined with parchment paper and spread evenly.
Refrigerate for 2-3 hours until set.
Remove the set chocolate and cut into bite-size pieces.
Sift cocoa powder over the chocolates to coat evenly.