Preheat the oven to 375°F. Line two large baking sheets with parchment paper.

In a medium mixing bowl, whisk to combine the flour, cocoa powder, baking soda, and salt.

In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl, using a handheld electric mixer), cream the butter, light brown, and granulated sugar on medium speed for about 3 minutes until lightened in color and fluffy.

Add the egg, vanilla and peppermint extract, and mix on low speed for 30 seconds, just until combined.

With the mixer on low speed, gradually add the flour mixture a few tablespoonfuls at a time, mixing just until combined between each addition.

Chop one-quarter of the peppermint bark (4 ounces, 113g) into small pieces like the size of the dark chocolate chips (1 cup, chopped). Break the remaining peppermint bark (12 ounces, 340g) into about 1-inch pieces (you will need about 24 pieces). Set aside.

Add the chocolate chips and smaller peppermint bark pieces to the cookie dough and mix on low speed just until combined.

Scoop cookies to be about 2 tablespoons in size (about 40g each) with a triggered cookie scoop or two spoons onto the prepared baking sheets, leaving about 2 inches of space between each cookie.

Bake the trays one at a time for 9 to 10 minutes until the edges are set and the top appears dry. Remove the pan from the oven and immediately press one of the larger pieces of peppermint bark into the center of each cookie.

Sprinkle the cookies with chopped candy canes while they are hot. Let the cookies cool on the pan for 5 to 10 minutes to melt the bark slightly. Transfer them to a cooling rack to cool completely.