1. Preheat oven to 350 °F and line a 9×9-inch pan with parchment paper.

2. Melt butter in a saucepan over low heat, whisk in cocoa powder until smooth and let cool slightly.

3. In a bowl, whisk sugar and eggs until thick and pale, then stir in the cooled chocolate mixture.

4. Add peppermint extract and whisk to combine, tasting and adjusting for desired mint flavor.

5. Sift flour and salt together and fold into the wet mixture until just combined.

6. Fold in chocolate chips, then pour batter into prepared pan and smooth the top.

7. Bake for 25 minutes or until the center is set with moist crumbs attached to a toothpick.

8. Cool completely on a rack, then sprinkle with crushed candy canes and cut into 16 squares.