Preheat oven to 300°F.
The oven needs to be on low heat.
Cut the butter into large chunks and put it into an oven proof dish.
Something like a souffle dish will work, but just make sure that the bottom of the pan isn't too wide, or the butter will cook too quickly and you won't have time to get that nice roasted flavor.
Put the butter into the oven for one hour.
At that time, the impurities will have separated from the butter, but it probably won't have darkened in color to show that it has that roasted flavor.
Keep checking the butter every 10 minutes until it darkens several shades.
Remove the butter from the oven and let it cool for about 10 minutes, and then spoon off the impurities on the top of the butter.
Pour the butter through a fine metal mesh strainer.
Store the clarified butter, covered, in a cool dry place.