1. Preheat oven to 350°F (175°C) and line a 9×9-inch baking pan with parchment paper

2. Melt butter and semi-sweet chocolate chips together until smooth, then stir in instant espresso powder

3. In a bowl, whisk sugar, eggs, and vanilla extract until fluffy, then pour in the chocolate mixture and mix until combined

4. Sift together flour and cocoa powder and fold into the wet mixture until smooth

5. Pour half the batter into the pan, sprinkle with crushed Oreo cookies, then cover with remaining batter

6. Drizzle peppermint extract over the top and gently swirl into the batter

7. Bake for 30–35 minutes until edges are set and center is slightly gooey

8. Cool completely in the pan, then sprinkle with crushed candy canes

9. Use a sharp knife to cut into squares, wiping the blade clean between cuts