Melt the sugar in a nonstick skillet, stirring almost constantly, until it becomes liquid and medium caramel in color. Watch it carefully! It will clump at first, then begin to melt. As the sugar melts, fill flan cups with very hot water. As soon as the sugar has caramelized, pour out the water from each cup one at a time and coat with caramel. Do this quickly – the syrup will harden almost instantly, and if it heats for even 30 seconds too long, it will turn to candy. Fill the cups with the flan mixture and place them in a bain-marie to cook. The easiest way to do this is to place the cups in a large empty pan, put the pan in the oven, and then pour water into the pan so that it rises to a level just below the rims of the flan cups. Bake for 45 minutes.

Remove the cups of flan from the oven and the bain-marie and refrigerate, preferably overnight, to allow the caramel to liquefy. When you’re ready to serve, run a knife around the edge of the cup, place a plate upside down on top of it, and flip it over so that the flan falls onto the plate topped with caramel.