Brown butter

Brown butter is butter that has been melted and cooked until the milk solids turn golden brown. It smells of toasted nuts and caramel. The French call it beurre noisette, "hazelnut butter", for its color and smell. It is used as a quick sauce and as a flavor in cookies, cakes and frostings.

How to do it

1. Cut the butter into even pieces and put it in a light-colored pan so you can see the color change. A stainless steel saucepan is ideal.
2. Melt it over medium heat, swirling the pan.
3. It will foam and sputter as the water boils off. Keep swirling.
4. After 3 to 5 minutes the foam settles and small brown specks form on the bottom.
5. When the specks are golden to hazelnut brown and it smells nutty, pour it into a heatproof bowl at once, scraping in the specks.

How to tell it is done

The sputtering stops, the butter turns amber, and the solids at the bottom are the color of hazelnut skins. It smells toasty, not burnt. From brown to black takes less than a minute.

Why it works

Butter is about 80% fat, plus water and milk solids. Once the water boils off, the milk proteins and sugars heat past the boiling point and brown through the Maillard reaction. The fat itself does not brown much. Clarified butter and ghee have had those solids removed, so they cannot brown the same way.

How to use it

Spoon it over fish, gnocchi, ravioli or steamed vegetables with sage, lemon or capers. Use it cooled in place of melted butter in cookies, blondies and financiers. Because some water has cooked off, a recipe may add a spoon of milk or water back.

Common mistakes

• Using a dark pan, so you cannot see when it is ready.
• Walking away. It goes from golden to burnt very fast.
• Leaving it in the hot pan, which keeps cooking it. Pour it out.
• Straining out the brown bits. They carry most of the flavor.