Preheat oven to 180ºC (or 160ºC fan forced) and make brownies according to packet directions.
While brownies are baking, start making the chocolate mousse. Break the chocolate into pieces and place in a heatproof bowl over boiling water, ensuring the bowl isn’t touching the boiling water. Stir until melted. Set aside to cool.
Place remaining eggs and sugar in a large bowl and beat with an electric mixer until thick and doubled in volume, approximately 5 minutes.
Fold the cooled chocolate and cacoa powder through the egg mix.
In another large bowl, beat the cream with an electric mixer until soft peaks form, then carefully fold half through the chocolate mix.
Place remaining cream and mousse in the fridge to cool for 30 minutes.
Once brownie has finished baking, set aside to cool completely. Once cooled, break into large chunks.
Place unwrapped candy canes into a sealed bag and break into pieces.
To create your trifle, layer ingredients in 8 glasses in order of brownie, crushed candy canes, cream and mousse and repeat until all the mixture is finished.
Sprinkle extra crushed candy cane pieces on top to serve.