Remember those little mints by the door at that restaurant you like? No, not that restaurant -- the nice-but-not-NICE-nice one. This recipe is most closely related to those little post-dinner courtesy mints -- but don't think they actually taste alike. These "mints" have a smooth, buttery flavor that's somewhat reminiscent of very thick frosting. And they're not necessarily minty at all: The texture of these little crisp-then-creamy confections lends itself very well to warmer flavors like coffee, chocolate, and cinnamon, too.
Buttermints are great as homemade party favors, since you can get multiple colors out of a single batch and mix and match as you please. Just remember to squirrel away a couple for yourself as a little after-dinner-at-home treat.
1. Combine the butter and the 4 cups confectioners' sugar in the mixer bowl. Beat on medium-high speed until the mixture is smooth and creamy, 6 to 8 minutes.
2. Add the peppermint oil and milk, and beat on medium speed until combined.
3. Lightly dust some confectioners' sugar onto a cutting board, and turn the dough out onto the board. If you're using food coloring, add 1 to 2 drops (or more for deeper color) and knead it into the dough with your hands until incorporated. If you're making multiple colors, divide the dough into several pieces first (one for each color) and add the food coloring to each piece, starting with 1 drop and kneading, adding 1 drop at a time, until the desired colors are reached. Gather each piece of dough into a ball.
4. Sift more confectioners' sugar over the cutting board. Divide the dough into 4 pieces (if you haven't divided it already), and set 3 of the pieces aside, loosely covered in plastic wrap to prevent them from drying out. Using your hands, and dusting them with confectioners' sugar as needed to reduce any stickiness, gently roll one piece of dough into a log about 1/2-inch in diameter.
5. Use a sharp chef's knife to cut the log into 1/2-inch pieces. Lay the pieces in a single layer on the prepared baking sheet to dry. Repeat with the remaining 3 pieces of dough, and allow the candies to dry at room temperature, uncovered, overnight.
Store the buttermints, layered between parchment or wax paper, in an airtight container at room temperature, away from light, for up to 2 weeks.
Coffee Buttermints: Replace the peppermint oil with 2 teaspoons coffee extract, 1 tablespoon instant espresso powder dissolved in 1 teaspoon hot water, or 1 tablespoon Trablit.
Chocolate Buttermints: Omit the peppermint oil, decrease the milk to 1 tablespoon, and beat 1 tablespoon Dutch-process cocoa powder in with the butter and sugar in step 2. Roll in cocoa powder before drying.
Cinnamon Buttermints: Replace the peppermint oil with 1/4 teaspoon pure cinnamon oil.
Harold McGee, the author of Keys to Good Cooking, is an expert on the chemistry behind food and cooking. McGee recently made his first trip to China, where he learned more about rice wine.