Preheat the oven to 350°F (175°C). Grease a 12-cup muffin tin thoroughly with butter or cooking spray, then coat the bottoms and sides with granulated sugar.

Press the egg yolks through a fine sieve into a large bowl to remove the thin membranes.

Add the coconut milk, shredded coconut, granulated sugar, and the orange liqueur or vanilla extract (if using). Whisk gently until smooth.

Spoon the mixture into the prepared muffin cups, filling each one about three-quarters full. Set the muffin tin inside a larger roasting pan and pour boiling water into the roasting pan until it reaches halfway up the sides of the muffin cups.

Bake for 25 to 30 minutes, or until the tops are set and a toothpick comes out clean.

Allow the tin to cool on a rack for about 5 minutes. While still warm, place a baking sheet over the tin and flip it over to unmold. If any quindims stick, run a small knife around the edges to release them.

Cool completely and chill for at least 2 hours before serving cold, topped with mint or grated coconut if desired.