Preheat the oven to 170C/325F/Gas 3. Spray an 8x8-inch square baking pan with baking spray and line with parchment paper. Set aside.

Place the butter, sugar, cocoa powder, instant coffee granules, and salt into a microwave-safe bowl, and microwave in 30 second intervals, stirring after each one, until the butter is melted and the mixture feels very warm to the touch.

Mix in the eggs, one at a time. Fold in the flour until fully combined, stirring until thick and shiny. Fold in the chocolate chips (they will melt into the batter, but it's fine! It helps produce a shiny top). Stir in the peppermint extract.

Pour the batter into the prepared pan, and spread out evenly. Bake for 30 -35 minutes, or until a toothpick inserted into the centre comes out almost clean with a few moist crumbs.

Sprinkle with crushed candy canes and allow to cool completely in the pan on a wire rack before cutting into squares.