Wash the pandan leaves. Wipe them dry and cut into 5 cm pieces.
Fry the tapioca flour in a wok together with the pandan leaves until it's very light and fluffy.
Make sure the wok is large enough so that the flour will not splatter out as you fry it.
Fry for around 75 minutes (on really low flame) until the flour becomes very light and slightly yellow and the pandan leaves turn crispy.
Set aside to cool down.
In a large bowl, sift together the flour with the salt and custard powder.
In a separted bowl, whisk the egg yolks with the sugar until pale and fluffy. Add the oil.
Alternately add to the egg mixture, parts of the flour mixture and parts of coconut milk.
Mix until getting a good firm dough (not too wet or too dry).
Roll out the dough around 1 cm thick (between two sheets of baking paper) and then cut shapes with help of cookie cutter.
Lay the cookies in a lined baking tray and bake in a previously pre-heated oven at 170 °C for 10 to 15 minutes.
(They must be dry but without too much color).