Clarified butter is butter from which water and milk solids like protein and sugar have been removed to leave pure milk fat.  As the name implies, it has a radiant clarity.  As the proteins have been removed, it can be heated to frying temperatures without burning.

Clarifying butter is simple.  If you gently heat butter in a pot, this is what happens:

• The milk fat becomes liquid.
• The water content begins to evaporate, gently bubbling to the surface.
• The light whey proteins form a foam on the surface.  Once the water content has been driven off, this foam dries and forms a crackly skin.
• The heavier casein proteins coagulate and fall to the bottom of the pot.

If you skim the layer of whey proteins from the surface of the butter as shown below, then decant the mixture to remove the casein on the bottom of the pot, you are left with clarified butter.  Easy!

The only trick is to keep the temperature high enough to evaporate the water, but low enough to avoid browning the mixture.  The lowest setting on most residential stoves works fine.  Leave the butter for an hour or two to separate into the components described above.

Commercial butter is typically around 80% milk fat, the remainder being water and milk solids.^[1]  You will no doubt remove some of the fat when you skim and decant, so the yield on clarified butter is closer to 70-75% of the original weight.  In other words, if you start with one pound of butter, you will end up with about 10-11 oz of clarified butter.

1. Gisslen, Wayne. Professional Cooking for Canadian Chefs, Sixth Edition. Page 810.