Preheat the oven to 180°C/350°F. Line a large baking tray with greaseproof paper or a silicone mat.
Melt the butter in a small saucepan. Set aside to cool for a few minutes whilst you prepare the rest of the ingredients.
¾ cup unsalted butter
In a medium mixing bowl, combine the all-purpose (plain) flour, cocoa powder, baking powder, baking soda (bicarbonate of soda) and fine sea salt. Stir together using a whisk, to ensure all the ingredients are evenly distributed.
1 ¾ cups all-purpose flour, 1 teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon fine sea salt, ¾ cup cocoa powder
In the bowl of a stand mixer, combine the brown sugar and granulated sugar with the slightly cooled (but still warm) melted butter. Mix on medium speed, just until well combined. (Alternatively use a large mixing bowl and an electric hand mixer).
1 cup soft brown sugar, ¼ cup granulated sugar
Add the egg, vanilla and peppermint extract to the butter and sugar mixture and continue to mix on medium speed until well combined.
1 medium egg, 1 teaspoon vanilla extract, 1 teaspoon peppermint extract
Add the flour and cocoa mixture and mix on low speed until no streaks of flour remain.
Add the chocolate chunks and chips to the cookie dough. Mix on low speed until evenly distributed throughout the dough.
3 ½ ounces peppermint bark, ½ cup dark chocolate chips
Use a medium cookie scoop to scoop and roll the dough into approximately 2 tablespoon-sized balls (you should get 20 cookies from this mixture) and place on the prepared baking tray. You should get 6-8 on a tray at a time.
Bake in the preheated oven for 8-10 minutes (mine are perfect after 8 minutes in a fan-assisted/convection oven) until lightly golden at the edges. They should still feel soft and underbaked in the centre – that’s what you want! They’ll continue to bake as they cool. Makes 20.