Start with fresh, room temperature butter
Put it in a mixing bowl or the bowl of a food processor with a paddle attachment.
Compose your flavors
You have lots of options, but limit yourself to a few well-chosen additions:
Herbs, spices, aromatics: Ginger, shallots, garlic, scallion, fresh herbs, cracked or ground spices, citrus zests just scratch the surface. Herbs should be very dry before mincing them and adding them to the butter.
Salt: Though you may prefer your plain butter unsalted, a little fine sea salt really helps bring out the flavor of all the ingredients in a compound butter.
Acid: Vinegar or citrus juice adds balance to the mix. Blend in a few drops at a time.
A touch of sweetness: Sweet compound butters, with a bit of honey or superfine sugar, are delicious on warm breads and waffles. They can also be great on savory dishes, like a sage and honey butter on fish.
Wild card flavors: There are lots of other additions that are worth experimenting with—anchovy paste, dried fruit, cocoa, green tea powder, various extracts, etc.
You can do this with a stand mixer, electric hand mixer, or a rubber spatula. In some cases, you’ll want all the ingredients to be incorporated very thoroughly. Other times, though, it might look cool to have added ingredients swirled in a marbled fashion.
Wrap the butter up tightly
Place the butter in the center of a sheet of parchment paper. (You can also use wax paper or plastic.) Roll the bottom half of the paper over the butter. With one hand hold the bottom layer steady and with the other hand pull the covered butter towards you. You wrap your fingers tightly around the butter or use the assistance of a bench scraper or sushi mat.
Twist ends and refrigerate until hardened, about two hours. It should keep in the fridge for several days. You can also freeze it for about a month—so if you have a few flavorful morsels that you want to preserve, blend them in some butter.
Plus, having some compound butter handy for a last-minute dinner saves you prep work and dish-washing.
Cut the chilled butter into little "coins."
An alternative to the fancy rolling method is simply to use the butter right away in its soft, spreadable form. Or you can spread it into a small ramekin before chilling it.
Place a pat of your compound butter creation on something warm and eat the melt-in-your-mouth results.
I licked the plate clean after eating these seared scallops with a compound butter of roasted garlic, vanilla bean, a few drops of bourbon (that the vanilla had soaked in), and salt. This was my favorite compound butter of the week.
A few compound butter combinations...
On steak, classic Maitre D’Hotel butter: chopped parsley, lemon juice, salt.
On asparagus, fiddlehead ferns, and other springtime veggies: minced shallots macerated in sherry vinegar, Dijon mustard, salt.
For my kids: cinnamon and superfine sugar swirl. They’ll eat it on just about anything.