Begin by making pandan juice. Blend the pandan leaves with 3/4 cup (180ml) water and squeeze through cheesecloth. You should be left with about 1/2 cup (125ml) of pandan juice. You will only use 2 tablespoons pandan juice, reserve the rest for another recipe.
Boil the sugar and remaining 3/4 cup (180ml) water until about 1 1/4 cup (300ml) syrup remains. Add the jasmine extract to the syrup.
Mix the rice flour and tapioca flour together. Alternate adding the syrup and coconut milk to the flour mixture until it is mixed well.
Divide the batter into two portions. Add the 2 tablespoons pandan juice to one portion and mix well.
Oil a 25 cm x 25 cm pan, or a couple of straight sided small loaf pans, liberally with the vegetable oil. Place the pan, or pans, into a steamer and heat for 3 minutes. Remove the pan and pour 1/2 cup (125ml) of the white batter into the pan to form one layer. Place into the steamer and steam for 5 minutes.
Remove the pan and pour in 1/2 cup (125ml) of the green batter. Place into the steamer and steam for 5 minutes. Continue alternating and steaming until the batter is all used up. The final steaming should take 10 minutes.
Cool the pan completely and cut the dessert into squares and serve.
You should be able to find pandan leaves in a good Asian market. If you can't, you can substitute other flavourings such as a little essence.