If you have a craving for the cookies long after the last girl scout has sold out of her annual stack of boxes, cheer up. This combination of dark chocolate cookie and semisweet coating—our take on a Girl Scout Thin Mint—is a year-round affair. Delicious at room temperature, these crisp, luxuriously chocolaty cookies are arguably better straight from the freezer.
What to buy: For this recipe, we preferred the pure minty flavor of peppermint oil rather than peppermint extract, which has a slightly chemical aftertaste. Peppermint oil can purchased at many nutrition stores or online. Professional pastry chefs use a type of chocolate known as couverture, which sets up nicely because it contains more cocoa butter than regular chocolate. The only trick is, you need to temper it. For this recipe, we used El Rey 58.5 percent dark chocolate Discos; they can be found at many specialty grocery stores or online. In our experience, it’s best to avoid tempering chocolate on a hot day or in an aggressively air-conditioned space. Chocolate behaves best at a room temperature between the mid-60s and low 70s Fahrenheit. Also, chocolate stays in temper for only a short time, so have everything ready to go and work quickly.
Make-ahead note: The cookies can be baked up to 24 hours in advance and stored in an airtight container until ready to coat.
To make the coating and finish: