Brown Butter (Beurre Noisette)

Cut the butter into even cubes and place in a light-coloured stainless-steel or enamel saucepan — never a dark pan, because you need to see the colour of the milk solids clearly. Set over medium heat. As the butter melts, it will begin to foam vigorously: this is water boiling off. Swirl the pan gently every 30 seconds rather than stirring, which can prevent even browning. The foam will rise, subside slightly, then rise again into a second foam — this second foam is the signal that the water is nearly gone and browning is about to begin. Watch the pan intently from this moment.

Once the second foam appears, tilt the pan and peer through the foam at the bottom of the pan: small golden-brown specks should be forming on the floor of the pan — these are the milk solids caramelising. Swirl constantly now. The colour will progress from cream to tan to hazelnut in a matter of seconds. The moment the specks reach a deep amber-hazelnut colour and the kitchen fills with the unmistakable scent of roasted hazelnuts, remove the pan from the heat. Carryover heat will continue cooking the butter for 30 seconds off the stove.

Pour the browned butter immediately into a cool, heatproof bowl to arrest the cooking — the pan is still very hot and will continue to darken the solids if you leave them in it. If using as a sauce immediately, squeeze in the lemon juice now; it stops cooking instantly and adds a bright lift that cuts the richness. Season with flaky salt if desired. The brown milk-solid sediment is the most flavourful part — do not strain it out unless the recipe specifically requires clarified brown butter. Use immediately while warm and fluid, or let cool to a golden paste for pastry applications.