Melt the chocolate in a double boiler or in a bowl over a pan of barely simmering water and stir until melted.
Put the biscuits into a freezer bag, seal and smash to crumbs with a rolling pin. Transfer to a mixing bowl and pour over the melted chocolate, add the cocoa powder and coconut milk and mix well.
Line a small baking tin with baking parchment then spoon the mixture inside. Place in the fridge to set for a couple of hours. Remove from the fridge and cut into squares. Using a spatula, remove the squares and put upside down on a plate to serve or into an airtight container and back in the fridge to eat later.
You can add freeze dried raspberries or strawberries to the mix to make extra tasty squares!