Peel and finely grate tapioca. Put grated tapioca on a piece of clean muslin cloth and squeeze out excess liquid into a mixing bowl. When the process is completed, allow the yellow liquid to settle, then pour away the top layer, leaving only the starch that has settled at the bottom of the bowl.
Combine grated tapioca pulp, sugar, the starch, instant coffee granules and water in a wok. Stir and cook until the sugar melts.
Line a square tin with greased aluminium foil or greased banana leaf. Grease the sides of the tin as well.
Pour the cooked tapioca into the tin. Level it with a spatula and steam for 20-25 minutes.
Remove tin from the steamer and use a fork to prick the surface all over. Set aside.
Combine all the ingredients for the top layer in a saucepan. Cook over medium low heat until it starts to boil. Bring saucepan away from the heat and stir until it turns into a runny paste. Stir well until it is even in texture then pour over the bottom layer.
Steam for about 15 minutes or until the surface sets. Remove and leave aside to cool completely before cutting into serving-size pieces.