• Pre-heat your oven to 180℃ Fan/370℉. Line a 12 hole muffin tin with muffin cases.
• In a small bowl, break up the dark chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn. Alternatively, set up a double boiler. Do this by placing a heatproof bowl over a small pot of simmering water. Add the chocolate to the heatproof bowl and stir until melted. 
• In a large mixing bowl, whisk together melted butter and both sugars. Add in the eggs, one at a time and mixing in between. Add the melted chocolate slowly and combine once again. 
• Add the flour, salt and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Scoop into the muffin tin holes, they don't rise much at all so use all the batter!
• Bake 20-25 minutes, until no longer wobbly. While still warm, create the indents by using a teaspoon measure, egg cup or end of a wooden spoon. Press into the middle, leaving tall sides. Let cool.

For the Filling

• Add the butter to a large mixing bowl. Beat with a whisk on high for a minute to soften.
• Add half the powdered sugar, whisk on high. Then add the remaining half with the peppermint extract and whisk everything on high until fluffy. Add powdered sugar/milk as required to meet your desired consistency.
• Remove half of the frosting into a bowl and set aside. In the bowl with the mixer, add a few drops of food color - so you end up with a bowl of pink/red frosting, and a bowl of white frosting.
• Set up a piping bag, spoon in the frosting - alternating colors. I find it easiest to use a spoon/small spatula and spread one colour up half the bag, and the other color on the other half the bag - so when you look at the piping bag, one side is white and one side is pink.
• Frost in swirls into the brownie cups.
• Crush the candy canes - use a food processor for the easiest option, but you can also place them in a ziplock bag, place between a kitchen (tea) towel, and bash with a rolling pin. Sprinkle this on top and serve!