Combine almond flour and cocoa powder in a bowl and mix well.
Melt unsweetened dark chocolate using a double boiler.
Add the almond flour mixture, erythritol, and vanilla extract to the melted chocolate and mix evenly.
Add coconut oil and mix the dough once more.
Spread the dough evenly in a small square mold or container.
Let it set in the refrigerator for at least 1 hour.
Cut into appropriate sizes and it's ready to serve.