Brown butter is one of those magical staples that you will find a million uses for. Among the sweets, think brown-butter cookies and brown-butter pound cake; for savory dishes, a dollop of brown butter on broiled fish or steamed leeks or grilled tomatoes or ... what have you.
Start by cutting cold butter into pats and distributing them more or less evenly over the bottom of a small, cold frying pan.
Put the pan over a low flame and let the butter melt gently.
When the butter has all melted, stand over the pan and watch it. Do not look away. Do not turn the flame up.
The milk solids will gradually brown. When it looks like around half of them are lightly browned, turn the flame off. More will brown in the residual heat.
After the pan is cool enough so that you can rest your hand on the bottom, stir the browned milk solids into the melted buttery part to distribute them evenly.
That's it. You've made brown butter.