Wash and chop the pandan leaves. Blend about a handful of pandan leaves with 1/3 cup water (about 100 ml), then strain to get the pandan juice and set aside. Blend the remaining pandan leaves with the coconut milk (about 3/4 cup or 200 ml), then strain to get the pandan-coconut mixture. Combine the sugar and pandan juice in a saucepan, stir to dissolve, and heat over low until it just comes to a boil. Remove from heat and let cool completely.

Crack the eggs into a bowl and gently beat with a fork, being careful not to create bubbles. Add the vanilla. Strain the eggs into a larger bowl, then add the cooled pandan-sugar mixture and mix well.

Grease the baking pan with oil and wipe off any excess with a paper towel. Place the pan in the oven and preheat at 400°F (200°C) for about 10 minutes.

In a separate bowl, mix the tapioca starch, baking powder, and rice flour. Sift this mixture into the egg mixture. Add 2 tablespoons of the pandan-coconut mixture. Sift the batter again for a smooth texture, then stir in 2 tablespoons vegetable oil. Remove the hot pan from the oven. Pour the batter through a strainer into the pan to create the honeycomb texture. Bake at 375°F (190°C) for 30 minutes, then lower the temperature to 300°F (150°C) and bake for another 15 minutes or until golden and cooked through. Turn off the oven, invert the pan, and leave the oven door slightly open until the cake cools. Good luck!