1. preheat the oven to 350°F and line an 8×8-inch pan with parchment paper

2. melt butter and chopped chocolate together over low heat then whisk in espresso until smooth

3. transfer to a bowl, stir in sugar, whisk in eggs one at a time, then add peppermint extract

4. sift in cocoa powder, flour, and salt and fold gently until just combined

5. fold in crushed Oreos or layer whole Oreos in the batter for extra texture

6. pour batter into the pan and bake for 25 minutes or until a toothpick comes out with moist crumbs

7. cool completely in the pan, then lift out and decorate with white chocolate drizzle and crushed candy canes

8. cut into 16 squares, wipe the knife between cuts for clean edges, and serve