French Cheese Soufflé with Aged Cheese

Preheat a conventional oven (no fan) to 200°C. Prepare four straight-sided ceramic soufflé ramekins, each with a capacity of 250 ml and a diameter of about 9 cm. Spread 10 g softened butter over their bottoms and sides, brushing upward from the bottom. Rotate the ramekins to coat the interiors with a thin layer of the 5 g flour set aside for dusting, shake out the loose excess and place them on one baking sheet.

Melt the remaining 30 g butter in a saucepan over low heat, add 30 g flour and whisk for about 1 minute without browning. Add the milk in several portions, whisking thoroughly after each addition so no lumps remain. Heat over medium heat, stirring, until the sauce thickens noticeably and begins to bubble gently, then cook for about 2 more minutes over low heat. Add the salt, pepper and nutmeg; the béchamel should be smooth and fall from the whisk into the pan in a wide ribbon.

Finely grate the Gruyère and stir it into the warm béchamel off the heat. Transfer the base to a large bowl and let it cool for about 10–15 minutes, stirring a few times, until lukewarm. Meanwhile, separate the eggs, collecting the whites in a separate clean, dry bowl. Stir the yolks into the lukewarm base one at a time until the mixture is uniform.

Beat the egg whites with an electric mixer for about 3–4 minutes until glossy and elastic. When you lift the beaters, the foam should hold a peak with a gently bent tip. Do not keep beating until the whites become dry and lumpy, as they will be harder to incorporate evenly into the base.

Stir about one-third of the whipped whites into the cheese base to lighten it. Add the rest in two portions, gently folding with a spatula from the bottom upward while rotating the bowl. Stop mixing when the large white streaks have disappeared and the mixture is still light and fluffy.

Divide the mixture evenly among the prepared ramekins, filling them to about three-quarters of their height. Gently level the tops and wipe any mixture from the upper rims. Leave several centimeters between the ramekins on the baking sheet and put them straight into the preheated oven.

Bake on the middle rack for about 20–25 minutes. Do not open the oven during the first 20 minutes so you do not disturb their rise. They should rise clearly above the ramekin rims and have golden, slightly springy tops; the centers should be set but still soft and fluffy. When you carefully move the baking sheet, the centers may quiver slightly but should not ripple like liquid. If the mixture in the centers is still liquid toward the end of this time, bake for about 3–5 minutes longer.

Use oven mitts to remove the ramekins, place each on a small plate and serve immediately, with one soufflé per portion. The soufflés gradually fall after leaving the oven, so serve them while still hot.