Pour the mixture into a greased and lightly floured mold and put it to bake in a moderate oven for about 40 minutes or until tender (check with a toothpick).
In the meantime, prepare the topping, by melting the butter in a tray on the stove. Mix it with the powdered sugar, cocoa and dilute the mixture with water, so that it is not too dense.
Leave the ready brownie to cool and cut it into squares. Cover the brownies with the topping and sprinkle them with plenty of coconut.
When serving, present the brownies covered with coconut on all sides.