In a mixing bowl whisk together the flour, cornstarch, baking soda, and salt until well combined. Set aside for now.
2 cups (240 g) all purpose flour, 2 teaspoons espresso powder, 1 teaspoon cornstarch, 1 teaspoon baking soda, ½ teaspoon salt
In the bowl of a stand mixer fitted with paddle attachment, cream together the butter, light brown sugar and granulated sugar on medium speed for 2 - 3 minutes or until the butter and sugars are well combined.
1 cup (226 g) unsalted butter, room temperature, 1 cup (200 g) light brown sugar, 1 cup (200 g) granulated sugar
On low, cream in the cocoa powder, eggs, vanilla extract and peppermint extract one at a time until smooth and well combined. Mix the dry ingredients into the wet until just combined. Gently fold in the chocolate chips until well combined.
¾ cup (60 g) Dutch processed cocoa powder, 2 large eggs, room temperature, 1 - 2 teaspoons (5 - 10 ml) peppermint extract , 1 teaspoon vanilla extract , 1 cup (170 g) chocolate chips
Cover the cookie dough and transfer to the fridge to chill for 30 minutes - 2 hours. Preheat the oven to 350 F (177 C) for about 30 minutes before baking the cookies. Line a large baking sheet with parchment paper.
Using a medium cookie scoop (2 tablespoons, 30 ml), scoop the chocolate chip chocolate cookie dough into ballsand place them onto the lined baking sheet about 3 inches (8 cm) apart.
Bake at 350 F (177 C) for 10 - 12 minutes until the edges are set and tops of the cookies are slightly puffed. As soon as the cookies come out of the oven, reshape any cookies using a biscuit or cookie cutter slightly wider than the cookie. In a circular motion, gently nudge the edges back into a round shape. While the cookies are still hot from the oven, sprinkle and gently press the crushed peppermint candy to the hot cookie. ¼ - ½ cup crushed peppermint candy
Cool the soft and fudgy cookies on the baking sheet for 5 minutes. Then transfer to a cooling rack to cool completely to room temperature and enjoy. Alternatively, melt dark chocolate or white chocolate, drizzle on top of each cookie or dip half of each cooled cookie in the chocolate and then top the wet chocolate with the crushed peppermint pieces.