Line a 20cmx20cm (7.8"x7.8") baking tin with baking parchment. Preheat the oven to 180c/350f.
Mix together all of the ingredients except the topping ingredients in a large bowl.
Spoon into the prepared tin and level it out - make sure it goes right to the edges.
Place in the oven to cook for 30 minutes.
Take out of the oven and leave to cool completely in the tray.
Melt the chocolate over a bain marie or in the microwave in 30 seconds bursts (stir in between each burst). Stir in the melted butter and pour/spoon over the top of the cooked coconut mixture (still in the tray).
Place in the refrigerator to set for at least 45 minutes, then take out of the refrigerator. Remove from the tray and place on a chopping board. Slice into 9 large squares, or 36 bite-size cubes.
These treat should keep for up to a week in a sealed container at room temperature or in the refrigerator..Nutritional Information is per serving, cutting the cake into 9 portions. Divide by 4 if cutting into 36 bitesize pieces.