Combine the coconut milk, palm sugar, and pandan leaves in a medium saucepan over low heat. Stir until the sugar is fully dissolved, about 4 to 5 minutes. Do not let it boil.

Remove the pandan leaves and let the coconut mixture cool for 10 minutes until it is just warm to the touch, not hot.

Crack the eggs into a mixing bowl and whisk gently until the yolks and whites are combined. Avoid whisking too vigorously or you'll create foam.

Pour the warm coconut mixture slowly into the eggs while stirring constantly. Add the fish sauce and jasmine essence if using.

Strain the entire mixture through a fine-mesh sieve into a pouring jug. Strain a second time if you see any egg strands remaining.

Let the mixture rest for 2 minutes to allow surface bubbles to settle.

Set up your steamer with water and bring it to a gentle simmer over medium-low heat. Wrap the inside of the lid with a clean kitchen cloth to catch condensation.

Divide the custard mixture evenly among 6 small ramekins or heatproof cups, filling each about three-quarters full.

Place the cups in the steamer in a single layer. Cover and steam for 20 to 25 minutes, until the edges are set and only the very center wobbles slightly when nudged.

Carefully remove the cups from the steamer and set on a wire rack. Leave uncovered for 30 minutes to cool, then refrigerate or serve at room temperature.