Île flottante — Vanilla Custard with Poached Meringues

Separate all the eggs. Put the whites in a large, clean, dry bowl and the yolks in another bowl; cover the yolks and refrigerate while you make the meringues. There must be no yolk and no fat in the whites, as either would make whipping harder. Measure out separate 60 g portions of sugar for each part of the dessert, and divide the milk into 500 g and 100 g portions; keep the smaller portion in the refrigerator.

Split the vanilla bean lengthwise and scrape out the seeds. Put the seeds and empty bean in a saucepan about 18–20 cm across with 500 g of milk. Heat until the milk is visibly steaming and small bubbles appear around the edges. Remove from the heat for 5 minutes to infuse, then take out the empty bean. Leave the seeds in the milk. Return the pan to very low heat before poaching the meringues, without bringing the milk to a boil.

Beat the egg whites with an electric mixer, starting at medium speed. Once the foam is white and starts to hold soft peaks, add the 60 g of meringue sugar in three additions. Continue beating until thick and glossy and able to hold its shape on a spoon, usually about 5–7 minutes in total. Stop before the foam becomes dry and lumpy. Do not add the yolks, and do not use the sugar reserved for the custard.

Keep the milk just below a boil: it should steam, with a few small bubbles around the edge, without bubbling. Using two spoons moistened in this milk, shape oval portions of meringue about 5–6 cm long; make about 12 from the whole mixture. Add 3–4 at a time, leaving room for them to expand. Poach for about 2–3 minutes, carefully turn with a slotted spoon, and cook for another 2–3 minutes. The meringues should hold their shape, feel gently springy, and be set all the way through, without raw foam in the center. Larger portions need the upper end of the cooking time. Lift onto a large plate and let drain briefly. After the last batch, transfer them to a container with a lid and refrigerate; save the milk drained onto the plate for the custard.

Strain the poaching milk and the milk drained onto the plate into a clean saucepan; do not discard this milk. Add the reserved 100 g of milk and heat until steaming again. Mix the yolks with the 60 g of sugar for the custard. Whisking constantly, pour about half the hot milk into the yolks in a thin stream, then pour everything back into the pan with the remaining milk. Heat over low heat for about 8–10 minutes, constantly sweeping a spatula across the bottom and sides. The custard should thicken noticeably and coat the back of a spoon in a thin layer; a line drawn through the coating should stay visible. Do not let it boil. As soon as it thickens, remove from the heat and pour through a strainer into a clean bowl.

Set the custard bowl in a larger container of cold water, making sure no water gets into the custard. Stir every few minutes and replace the water as it warms until the custard is no longer warm, usually about 20–30 minutes. Cover the surface with plastic wrap suitable for contact with food and refrigerate for at least 2 hours. Keep the meringues separate in the refrigerator so they do not soak up custard while chilling.

Gently stir the chilled custard and divide all of it among four bowls. Place three drained meringues on each portion. Serve immediately after assembling. You can make the custard and meringues earlier the same day; keep them separately covered in the refrigerator and use within 24 hours.