Blanch the almonds and grind them with the skin with 1 and 1/2 cup of water. Strain the liquid. Put this liquid in a pan and reduce it for 2 minutes. Let it cool for 5 minutes.
Blend almond milk reduction, banana, cocoa powder, sugar and vanilla essence in a food processor. Put this mixture in a bowl and keep it in the freezer. Let it be there for an hour.
After an hour remove it and blend it again with a hand blender for 2 minutes. Return the bowl to the freezer and let it remain for an hour.
Ice cream will be ready to eat.