Mint Chocolate Chip Cookies

Preparation

1. Step 1

   Prepare the cookie base: Heat oven to 325 degrees. Grease a 9-inch square baking pan (using a butter wrapper is especially easy here). Line the pan with parchment paper so there’s overhang on two sides.

2. Step 2

   In a medium bowl, using a flexible spatula or wooden spoon, cream together the butter and the powdered sugar until smooth. Whisk in the egg white, peppermint and vanilla extracts, and salt until smooth. Switch back to the spatula or spoon, and stir in the flour until just combined.

3. Step 3

   Spread the dough as evenly as you can across the prepared pan. Bake, rotating halfway through, until lightly golden on top with golden-brown edges, 25 to 30 minutes. Let the cookie cool completely in the pan, about 1 hour. (It will harden as it cools.)

4. Step 4

   Prepare the topping: Using a sharp knife, finely chop the dark chocolate into thin chips, like wood shavings. Heat the white chocolate in 15-second intervals in the microwave, stirring between each, until melted and smooth. Stir in the olive oil, peppermint extract and food colorings. You should have a minty blue-green color. Using a small offset spatula, spread this evenly across the top of the cooled cookie, leaving a ½-inch border. (You’ll slice them off later.)

5. Step 5

   Top the cookie with the dark chocolate chips while the white chocolate is still wet. (Alternatively, you can grate the chocolate over using the largest holes of a box grater.) Refrigerate or freeze the pan until the white chocolate is fully set.

6. Step 6

   Remove the cookie from the pan and transfer to a cutting board. Slice off the four naked edges to discard or to snack on later. Cut the remainder into long, irregular shapes, starting at the corners. These cookies keep fresh in an airtight container for up to 3 days.