Blend 15 of the pandan leaves with 2 tablespoons of water and 2 tablespoons of coconut milk. Sieve the blended pandan leaves and set aside the extract.
Grease a 7-cup bundt pan or cake pan.
Using a mixer or a whisk, whisk together the eggs, oil, and sugar until the sugar has dissolved and the eggs are whipped. Mix the rest of the coconut milk and pandan extract. Sift in the flour and baking powder and mix the batter.
Pour the cake batter into the prepared pan. Tap onto a surface to remove air bubbles in the batter.
Pour 1.5 cups of water into the Instant Pot and place the steamer rack inside. Place the cake pan on the rack.
Close the lid and select Pressure Cook on High for 40 minutes. Natural release pressure for 10 minutes and quick release remaining pressure.
Remove the cake pan and allow it to cool completely before removing the cake.