Grease banana leaf with coconut oil or butter. Line an 8-inch square pan with the oiled banana leaf.
Place rice and water in a rice cooker. Cook until rice is done al dente.
Boil coconut milk, sugar, and salt in a wok over medium heat. Reduce heat; simmer for about 15 minutes, until sugar is completely dissolved. Add cooked rice; stir constantly for 5 to 10 minutes, or until most of the coconut milk has been absorbed. Biko is cooked when mixture oils up and the rice no longer sticks to the sides of the wok.
Pour hot into prepared pan; flatten with an oiled spatula. Cut into 2-inch squares with an oiled knife or spatula. Top each square with grated coconut and/or coconut curds.
Serve hot or cold. Refrigerate leftover biko covered, in the baking dish, and consume within 5 days. Wrap leftovers in plastic wrap and freeze up to 6 months; thaw overnight in fridge before serving; serve at room temperature or warm by steaming for about 10 minutes.