6. Cool completely in the pan on a wire rack—several hours at room temperature or until firm. You may refrigerate to speed this (about 1–2 hours). If you use the freezer to firm them quickly, freeze only 20–30 minutes and allow a brief thaw before cutting (fully frozen bars are difficult to cut cleanly).
8. Line a baking sheet with parchment for the chocolate-dipping step. Place the bars on the sheet and chill or freeze until firm for easier dipping (freeze 20–30 minutes or refrigerate until firm). Meanwhile, melt 8–12 ounces dark chocolate in a heatproof bowl set over simmering water (double boiler) or in the microwave in short bursts, stirring until smooth.