1. Preheat oven to 350 degrees. Grease a 9×13″ pan with butter or cooking spray and line with parchment paper, making sure there is overhang on all 4 sides to assist with removing the brownies. Butter the parchment paper.
2. In a medium bowl, whisk together the cocoa and boiling water until smooth. Add the chopped bittersweet or semi-sweet chocolate and mix until melted. Stir in the melted butter and oil until the mixture is smooth and all ingredients are incorporated.
3. Add eggs, egg yolk, and vanilla and whisk until thoroughly combined, then stir in the sugar.
4. Add flour and salt and stir into the chocolate mixture until thoroughly incorporated.
5. Stir in chopped peppermint bark.
6. Pour/scrape batter into the prepared pan, smoothing the top. If desired, sprinkle crushed peppermint candy on top.
7. Bake at 350 degrees for 35-40 minutes or until a toothpick or cake tester comes out clean. Underbaking will result in fudgier brownies.
8. Remove pan from oven and transfer to a baking rack to cool for 1-2 hours. Don’t be tempted to cut the brownies earlier; the long cooling period is essential to a crumble-free texture and a firm bite.
9. Once cool, lift the brownies from the pan using the parchment overhang (this is more easily done with two people if you have an extra set of hands around). If there is any residual warmth, allow the brownies to continue to rest until completely cool.
10. Using a sharp knife, cut the brownies into your 24 two-inch brownies portions.

The brownies freeze beautifully – once cut, wrap them individually and stack in a plastic freezer bag. They defrost quickly and retain a perfect texture for up to three weeks.