1 cup coconut milk
5 tablespoons palm sugar
4 tablespoons cane sugar
3 pandan (screwpine) leaves
4 large eggs
Set up a double boiler. Bring water to a boil and turn it down to medium-low heat. Melt sugar in coconut milk in the double boiler. Make sure the bottom of the top pot is not in contact with the water in the bottom pot. The water should be at a very gentle simmer.
Cut root end of pandan leaves and clean under running water. Bruise leaves slightly to help release its flavor, then tie them into a knot and add to mixture. When sugar has melted, which should happen very quickly, remove the pot of mixture from heat and let cool for a few minutes.
Whisk eggs well, then strain into mixture and carefully stir until combined. Place the pot of mixture back in the double boiler on medium-low heat. Cook, stirring constantly with a heat-resistant silicone spatula, for about 60 to 70 minutes. Use the spatula to scrape the side and bottom of the pot to ensure even cooking. The mixture will gradually thicken, noticeably so after 40 to 45 minutes.
If at any time lumps start to appear, remove mixture from heat immediately and stir or whisk until smooth. This happens when the mixture is overheated, resulting in the eggs curdling, so reduce heat before continuing to cook. Alternate between stirring and whisking to reduce lumps. If necessary, blend mixture with an immersion blender (without pandan leaves).
Once the mixture reaches a spreadable custard-like consistency, remove from heat. It will continue to thicken as it cools. Remove pandan leaves. Cool completely before transferring to a jar and storing in refrigerator. Makes about 1 cup of kaya.