Brown butter: butter heated to the point of separation, allowing the milk solids to be exposed to heat and start to cook- turning brown.
Why would you want to brown butter? Because butter is amazing, and brown butter is even more amazing. You heard it here first, folks. Butter is a magical substance- basically, the fat is emulsified with water, so when you heat it, the solids can separate. This is a similar method to clarifying butter, except you want to keep the milk solids.
Any time you are using melted butter in a dish that could use some extra punch or depth, you can brown the butter. This will lend a caramelly, nutty flavor to the butter, as the milk solids will actually start to cook and turn brown.
Very easy to do- put your butter in a medium saucepan, turn the heat to medium, and start melting it. It will go through a few different phases, but the last one you want is when the foam starts to turn brown. Check out the photos below for a step-by-step!
Looking for something to use this concoction in? How about some brown butter caramel bars?