Make the caramel: In a small saucepan, combine the sugar and water over medium-high heat. Cook until the sugar has dissolved and the mixture turns amber in color, 6 to 8 minutes. Divide between 6 shallow 4-ounce ramekins, swirling the mixture around to coat the bottom surface completely.
Make the custard: Preheat the oven to 350º. Combine the pandan leaves and water in a blender and purée. Strain through a fine-mesh sieve, discarding the solids. Transfer 2 tablespoons of the liquid to a medium bowl, along with the vanilla and the eggs. Whisk until smooth.
In a small saucepan, combine the coconut milk, whole milk and sugar over medium heat. Cook until the sugar is dissolved and the milk is just beginning to steam, 2 to 3 minutes. Remove from the heat and slowly whisk in the egg mixture until smooth.
Place the prepared ramekins in a roasting pan and strain the custard into each dish, filling up to the tops. Fill the pan with enough boiling water to cover the bottom half of each ramekin.
Transfer to the oven and bake until the flan is set, 30 minutes. Remove from the oven and let cool completely, then refrigerate until the custard is firm, 4 hours.
To serve, run a paring knife around the inside of each ramekin, then invert the flan onto a plate.