[Green Layer (A)]: Combine rice flour and tapioca flour in a mixing bowl. Add coconut milk and salt. Mix, then leave aside for 10 minutes. Strain the batter to remove any lumps.
Put sugar, water and screwpine leaves in a saucepan. Bring to a simmering boil - ensure all the sugar dissolves. Strain the syrup and set aside to cool for 5-10 minutes.
Mix syrup and rice flour batter together. Add pandan juice to mix.
[Sago Layer (B)]: Soak sago for 10-15 minutes until plumped. Drain and cook in a saucepan with 1 cup water for 1-2 minutes. When sago turns transparent, drain and rinse under running water. Drain and put aside.
Combine rice flour and tapioca flour. Add water and thick coconut milk, and mix well.
In a saucepan, bring sugar, water and screwpine leaves to a simmering boil for 2-3 minutes and heat until sugar dissolves completely. Strain and leave to cool slightly.
Add syrup into the batter to mix. Stir in sago and mix in colouring.
Heat a 22cm square cake pan in a steamer for 5-6 minutes. Pour in one ladleful of green coloured batter into the prepared pan. Steam for 4-5 minutes.
Add another ladleful of sago or yellow batter over the green layer. Steam for 4-5 minutes.
Alternate the layers until you come to the final green coloured layer. Steam for 30-40 minutes over a medium-low heat until the top layer is set. Remove and leave to cool completely before cutting into slices.