Make the brownies:

1. Preheat the oven to 350°F. Grease a 9-inch square baking pan and line it with parchment paper so that it hangs over two sides to make it easy to lift the brownies out of the pan when baked.
2. Melt the chocolate with butter in a medium heatproof bowl over a pan of simmering water. Make sure the bottom of the bowl does not touch the water, or you will burn the chocolate. Whisk until melted and smooth. Remove from heat and add sugars into the chocolate mixture and whisk until completely combined. Let the chocolate mixture cool for a few minutes.
3. Add in eggs, vanilla extract, and mint extract, and beat with a hand mixer on medium speed for 2 minutes.
4. Add in flour, cocoa powder, and salt and fold together using a large silicone spatula until just combined.
5. Transfer the thick batter into the prepared baking pan.
6. Bake for 30-35 minutes, until a toothpick inserted comes out clean with moist a few moist crumbs attached.
7. Place the baking pan on a wire cooling rack to cool completely.

Make the peppermint ganache topping:

1. Place chopped chocolate into a medium mixing bowl.
2. Heat the heavy cream in a small saucepan until it begins to simmer. Immediately remove from heat before it begins to boil.
3. Pour hot cream over top of the chopped chocolate and let it sit for 5 minutes to allow it to soften the chocolate. Use a spoon to slowly stir until completely smooth and creamy. Stir in the peppermint extract.
4. Spread the ganache evenly over the cooled brownies.
5. Sprinkle crushed candy canes on top.
6. Refrigerate for 1 hour to allow ganache to set. Then, use a sharp knife to cut the brownies in to 16 squares and serve. For clean cuts, wipe the knife after each cut.