Butter Cookies with Marbled Mint Icing

Preparation

• Cookies

  • In a bowl, combine the flour and salt.
  • In another bowl, cream the butter and icing sugar with an electric mixer. Add the egg and mix until smooth. With the machine running on low speed or with a wooden spoon, stir in the dry ingredients until the dough is smooth.
  • Using a rolling pin, roll out the dough between two sheets of parchment paper until ¼ inch (5 mm) thick. Place the dough on a baking sheet. Refrigerate for 1 hour or until the dough is firm.
  • With the rack in the middle position, preheat the oven to 350°F (180°C). Line two baking sheets with silicone mats or parchment paper.
  • On a work surface, using a ruler and a knife, cut the dough vertically into strips 2 inches (5 cm) wide (see note). Cut the strips diagonally into diamond-shaped cookies about 1 ½ inches (4 cm) wide. Place the cookies on the baking sheets. Reuse any dough scraps to make more diamond-shaped cookies.
  • Bake one sheet at a time for 12 minutes or until the bottoms and sides of the cookies are lightly browned. Let cool completely on the baking sheets, about 30 minutes.

• Icing

  • In a bowl, whisk the egg white, icing sugar and mint extract with an electric mixer for 5 minutes or until smooth and silky. Add water, as needed, if the icing is too thick.
  • Transfer the icing to a small bowl. Place a few drops of green and turquoise food colouring on the surface of the icing. Using a toothpick, delicately mix the icing and food colouring to achieve a marbled effect.
  • Dip the cookies one at a time in the icing, covering about ½ inch (1 cm) of one of the long sides. Shake off some of the excess icing and return the cookies to the baking sheet. Add more food colouring to the icing as needed. Let the cookies rest for 3 hours or until the icing has set. The cookies will keep for 2 weeks in an airtight container at room temperature, or for 3 weeks in the freezer.