Clarified butter is a pretty important ingredient in the professional cooking and baking worlds, so knowing how to clarify butter is equally important. You see, whole butter isn't really 100% butter. American butter is actually only about 80 - 81% butter fat, maybe 1 - 2% milk solids, and the rest is water. That's right, water. European butter is closer to 82 - 83% butter fat, which is why bakeries that use it tend to have richer-tasting pastries. The problem is, milk solids burn pretty easily. In fact, because of them, whole butter burns at around 250F. When you remove the milk solids, the smoke point for butter actually goes up to about 350F. Technically, you could deep-fry at this temperature, but you probably wouldn't want to with butter.
The process is pretty easy. First, you'll need a container to hold the butter. Each stick of butter is 1/2 cup, so it's pretty easy to figure out. Just make sure you leave a little extra room at the top to keep from spilling. In my example, I used two sticks of butter, so my bowl holds perhaps 1 1/4 to 1/2 cups. If I were you, I'd use a resealable plastic container.
Second, you'll need a pan big enough to hold your container. You might also want a tea towel to put at the bottom of the pan. Put a couple of inches of water in the pan, and then put your container in the water. You'll probably want to make sure the water comes at least half-way up the side of the container, but be careful not to get any inside the container. If some splashes in, it's not the end of the world. Your pan will probably look something like this:
Now, put the pan on the stove if you haven't already, and turn the heat to low. Low, I said! This won't be a fast process, but it also won't be very labor intensive. You can leave the room, but don't leave the house. Make sure you drop by every 10 minutes or so to check on things. Don't worry, the tea towel won't burn, because it's in the water. And if you leave the heat on low, then any plastic containers you use won't melt, because the towel will protect them from the direct heat of the stove. Let the butter slowly melt, until it's completely melted. Go ahead and turn the heat off, and let the butter cool on the counter for an hour or so. It should look something like this:
What happened? Well, water is heavier than fat because it's more dense, so the fat will float to the top and the water will sink to the bottom. This is also helped by the fact that water and fat repel each other anyway. But the milk solids are even lighter, so they float to the top of the butter. In a fast-paced restaurant setting, the solids would probably be skimmed with a spoon, leaving a thin layer of water on the bottom and a thick layer of melted butter on the top. They don't worry so much about the water, because it'll just evaporate when they cook with it. The milk solids, which would burn, are now gone. But we have a little more time, so we're going to take this just another step.
When the butter has reached room tempurature, go ahead and put the lid on the container (or wrap it in plastic wrap) and move it to the refrigerator overnight. In the morning, you'll have a solid layer of fat, with a liquid layer of water on the bottom and that layer of milk solids on top. If you turn it on its side, it would look something like this:
See that layer of water in the bottom? Now all you need to do is scrape the milk solids off the top with a butter knife, and then remove the hunk of butter and pour out the water. Now you have a nice little hunk of 100% butter fat ready for, well, lots of things. You know that fancy restaurant you go to because you just love their sauteed vegetables? Those vegetables were probably sauteed in clarified butter. That steak was probably cooked in butter too. No, I'm not talking about your local chain restaurants. Clarified butter is too expensive, so they're probably using some sort of oil. I'm talking about the really nice restaurant, the one that you took out a second mortgage to dine at, because you saw the chef on TV. Chances are they have a gallon of clarified butter on the line that all of the cooks share.
What else can you use clarified butter for? It's big in the pastry world as well. You can brush bread with it before baking it, or after it comes out of the oven. There's a world of pastries that you can brush it on, in fact. And when working with phyllo dough, what better to brush it with than clarified butter? The possibilities are nearly endless.