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