Place the butter into a microwave safe cup. (A Pyrex 16 oz measuring cup is ideal.) Nuke the butter at 20% power. Watch closely until the fat layer separates. This will be obvious.
Allow the mess to cool slightly. Skim the congealed scum from off the surface. Pour the clear, yellow oil carefully from the cup into a small bowl - allowing the residue at the bottom of the cup to remain.
Clarified butter can be used in place of olive, peanut, etc. for sauteing. Once the solids are removed from butter (by heating and decanting), its flash point increases, and the over-browning of food due to high heat is reduced.