Unsalted butter slowly melted just long enough to toast the milk solids, past the clarified butter stage to create a nutty, fragrant ingredient the colour of hazelnuts used in financiers, madeleines, viennoiserie and other pastries.
It also used as a sauce on fish and poultry dishes.
If you cook it longer so it goes darker and is almost burnt, it’s beurre noir, black butter, mixed with lemon juice/vinegar and parsley; often served with raie (skate).
Beurre de noisette, however, is butter made out of hazelnuts.
Image by Andrew Malone