In a high speed blender blend the chickpeas until it forms a smooth consistency.
Stir in all the other ingredients and combine well with a spoon. It should form a dough like consistency, and you may have to add an extra tablespoon of milk or two if it looks too dry!
Press with hands into a lined tin. If using the topping of chocolate, melt the chocolate in a double boiler and pour over the mixture in the lined tin.
Place in fridge to firm overnight, or for a minimum of 3 hours before serving!