Heat the oven to 325°F (165°C). Brush six 3-ounce metal molds or small ramekins with half the melted butter. Dust with the extra tablespoon of sugar and shake out the excess. Set them in a shallow roasting pan.

Rub the coconut and 3/4 cup sugar together until evenly moist. Gently push the yolks through a sieve into a bowl, leaving any membrane behind. Fold in the coconut mixture and remaining butter until uniform, keeping air bubbles to a minimum.

Divide the mixture equally among the molds. Place the roasting pan on an oven rack and carefully pour hot water into the pan to reach halfway up the molds. Bake 28–40 minutes, until the coconut top is lightly golden, the custards are set and their centers reach at least 160°F.

Lift the molds out of the water. Cool about 30 minutes until warm, loosen the edges with a thin knife and invert each onto a plate. Refrigerate if serving later.