Whisk coconut milk, sugar, egg yolks, cornstarch, and salt in a saucepan over medium heat. Stir for 5-7 minutes until thickened. Stir in vanilla; cool.
Mix flour, sugar, baking powder, and salt in a bowl. Combine coconut milk, eggs, pandan extract, and butter in another bowl; mix with dry ingredients.
Heat a griddle over medium-low; coat with cooking spray or butter. Pour 1/4 cup batter per pancake; cook 2-3 minutes until bubbles form, then flip and cook 1-2 minutes.
Spread 1-2 tbsp custard on one pancake, top with another pancake. Garnish with coconut, mango, and syrup or honey. Serve warm.