Preheat the oven to 180C/350F/Gas 4. Grease and line a 23cm/9in square tray with parchment paper.
For the brownie, whisk the eggs and sugar in a large bowl until pale and thickened.
Melt the milk chocolate, dark chocolate and butter in a large heatproof bowl, set over a pan of simmering water (do not allow the bottom of the bowl to touch the water). Once melted set aside to cool for a few minutes.
Stir the melted chocolate into the egg mixture to combine.
Carefully fold in the sifted flour, spices, baking powder and cocoa powder, if using, into the mixture.
Spoon the brownie mixture into the prepared tin, smoothing the top with a palette knife.
Bake in the oven for 20-25 minutes, or until the center is just set and the top springy to the touch and beginning to crack. Set aside to cool in the tin.
For the chocolate sauce, heat the cream gently in a pan. Place the milk chocolate in a large bowl and pour the hot cream over, whisking to combine.
For the mint cream, whip the double cream and icing sugar together in a large bowl until soft peaks form when the whisk is removed. Fold in the shredded mint.
When the brownie is completely cool, cut into squares and place in serving bowls. Drizzle with the chocolate sauce and top with a spoonful of whipped mint cream. Sprinkle over the crushed honeycomb to serve.