Weigh the butter and oils into a heatproof jar.
Set the jar into a pan containing several inches of water, forming a double boiler setup.
Place the pan over a medium low burner until the butter completely melts.
Remove the jar from the heat and pour the hot mixture into a tall narrow mixing container, like a 4-cup Pyrex measuring pitcher.
Place in the refrigerator to cool, about 35 to 55 minutes, or until it turns opaque and develops a solid layer on top.
You want the chilled mixture to be on the more solid side, but not rock hard.
Using a hand mixer, beat for a minute, then add essential oils, if using.
Continue whipping until light and fluffy.
If the butter seems too stiff while mixing, blend in more oil, about 1/4 ounce (7 g) at a time.
You can scoop into containers right away, but for a fluffier butter – cover the butter and let it sit overnight and rewhip it with your mixer the next day, adding more oil if needed to make it a lighter consistency, then fill into containers.
Some mixers will make a fluffier and lighter product than others, but this recipe should fill about 2 to 3 four-ounce jars.