Preheat oven to 350°F.

Heat milk with vanilla bean halves in a small saucepan over moderate heat until hot. Remove from heat, cover, steep 20 minutes.

Prepare custard dishes by setting them in a dishtowel-lined cake pan. Cook sugar in a small, non-stick (ceramic) skillet over medium-low heat, swirling skillet to help sugar melt evenly, until melted and deep caramel, 1-2 minutes. Immediately pour into (4) 5-6 ounce custard cups or ramekins, tilting the cups as needed to coat the bottoms. Let the caramel cool while you mix the custard ingredients.

Whisk together the whole egg, the egg yolk, sweetened condensed milk, and a pinch of salt until smooth. Discard the vanilla bean pod from the steeped milk and gradually whisk the milk into the egg mixture.

Divide the custard among the custard dishes. Fill the cake pan with boiling water until the water level is half way up the sides of the custard dishes. Cover loosely with a sheet of foil, in the middle of the oven until the custard is set, but still trembles slightly, 35-40 minutes.

Remove from the oven and take the custard dishes from the water bath, placing them on a wire rack to cool. Chill, uncovered, at least 2 hours before serving. Unmold the flans by running a knife or cake spatula around the edges to loosen and invert onto dessert plates.

Flans can be made ahead and kept chilled in custard cups, uncovered.

Bon Appétit!