Soufflé au fromage

03 — Method

1. Preheat the oven to 200 °C (400 °F) fan. Butter the 22 cm (9 in) soufflé dish generously and dust it with grated Parmesan, tapping so it coats the sides evenly. This is ESSENTIAL for the soufflé to rise properly.
2. Separate the 6 eggs VERY cleanly: 6 yolks in one bowl, 6 whites in another. NOT a trace of yolk in the whites (or they won’t whip to stiff peaks). Keep the whites at room temperature.
3. Make the béchamel: melt the unsalted butter in the medium saucepan over low heat without browning. Sprinkle in the flour and whisk hard for 2 minutes to make a pale roux.
4. Pour the hot whole milk into the roux in a thin stream, whisking hard and constantly to prevent lumps, for a perfectly smooth béchamel.
5. Bring to a simmer and cook over low heat for 5 minutes, stirring constantly with a wooden spoon, until it coats the spoon. Season with fleur de sel and plenty of pepper. Add the mustard and the pinch of freshly grated nutmeg.
6. Off the heat, whisk in the 6 yolks one at a time so they blend in without cooking. Stir in the grated Gruyère and half the Parmesan.
7. Whip the 6 whites to stiff peaks with an electric whisk and a pinch of salt — they should hold a peak when you lift the whisk. Fold them gently into the warm cheese béchamel with a silicone spatula IN 3 ADDITIONS.
8. Pour the mixture gently into the soufflé dish, three-quarters full. Run your thumb around the edge to make a groove (for the classic “top hat”). Bake for 30 minutes at 200 °C (400 °F) and NEVER open the oven (it will fall). Serve IMMEDIATELY.