Preheat Oven & Line Tray: Preheat the oven to 356ºF (180ºC) fan-forced and line a baking sheet with parchment paper, set aside.
Prepare Mixing Equipment: Set up your stand mixer with the paddle attachment, or prepare a large mixing bowl with an electric hand beater.
Cream Butter, Sugar & Extract: Add softened butter and powdered to the bowl and beat on medium-high for 1 minute, scraping down the sides with a spatula. Add the peppermint extract and beat until combined.
Incorporate Dry Ingredients: Sift over the flour and cornstarch into the mixture. Beat on low-medium speed for 30 seconds until a crumbly dough forms. Turn off the beaters and finish bringing the mixture into a dough with your hands of spatula.
Shape Cookies: Scoop out 1 level tablespoon (25g / 0.9oz) of dough per cookie, roll into balls, and place on the baking sheet, do not flatten, keep them as balls, leaving a 2-inch gap between each.
Bake Cookies: Bake for 12-15 minutes or until edges are lightly golden and the middles and tops are pale.
Cool & Coat in Powdered Sugar: Let the cookies cool on the baking sheet for 10 minutes. Then gently roll each cookie in powdered sugar to coat, and place them onto a wire rack to cool completely. Enjoy!
Notes
Store: Place cookies in an airtight container at room temperature for up to 1 week to keep them fresh.Freeze: These cookies freeze well without losing their texture. Place in a freezer-safe container or bag with parchment paper between layers, then label and freeze for up to 2 months. Thaw at room temperature before serving.