1. Stir together confectioners' sugar, corn syrup, 1 tablespoon water, peppermint extract, and butter until a dough forms. Transfer to a work surface lightly dusted with confectioners' sugar and knead until smooth, dusting dough with more sugar as necessary, until no longer sticky. Form into a flat disk, place between two pieces of parchment, and roll out to a 1/4-inch-thick round. Remove top piece of parchment and generously dust with confectioners' sugar. Replace parchment and flip. Remove parchment from other side and generously dust with confectioners' sugar. Stamp out shapes with a 1 1/2-to-2-inch heart-shaped cookie cutter. Transfer cutouts to a parchment-lined baking sheet. Gather scraps, reroll, and stamp out more hearts. Let stand, uncovered, until hard and dry, about 2 hours and up to 1 day.

2. Balance one heart on a fork, with tip of heart facing end of tines. Dip into chocolate until fully submerged; lift up and gently shake fork back and forth to remove excess chocolate. Scrape bottom of fork against side of bowl to remove any remaining excess chocolate. Tilt handle of fork upward and allow heart to gently slide onto a parchment-lined baking sheet. Repeat with remaining hearts and chocolate. Let stand until chocolate is hard and dry, about 1 hour. Serve, or store in an airtight container at room temperature up to 1 month.