Browned butter is pretty much what it sounds like: butter that has been cooked until it is brown. The slightly more formal name for this is “beurre noisette,” or hazelnut butter – a double reference to the light brown color of the cooked butter and the lovely nutty flavor that it acquires during the cooking process.
If you’ve ever cooked with butter, using it to grease a frying pan before cooking eggs, for instance, you probably know that it is very easy to burn butter. The milk solids in butter have a low smoking point compared to pure fat, which means that while oil and shortening can take very high heats and be stable, butter cannot. But their ability to take the heat also precludes them from being able to achieve the browning that butter can. The browning of beurre noisette is a result of the milk solids in the butter cooking, toasting, and taking on a deep flavor and brown color. It doesn’t take long to go from brown to black (beurre noir), so stand by the stove while you’re cooking.
To make browned butter, simply melt some butter (I prefer unsalted for this) in a small saucepan on the stove. Continue cooking it on medium-high heat until the butter boils and begins to brown. Don’t worry if your butter bubbles or foams; just keep cooking it. When the butter begins to brown, you will see specks of darker brown develop at the bottom of the pan. Stir these up and cook until the butter has a nice and even dark honey color. Remove from heat and transfer to another container to cool.
Browned butter can be used in baking in place of regular melted butter and is a great way to finish off a simple vegetable or pasta dish and really kick up the other flavors.