Line a small Weber Drip Tray with grease proof paper and grease lightly.
Melt the dark chocolate and butter in a pan (either on the barbecue or on the hob)
Remove from the heat and add the caster sugar. Stir well until the sugar has dissolved.
Beat the eggs in a large bowl and add the chocolate mixture.
Roughly chop the milk chocolate and add to the mix. Finally, stir in the flour and pour into a prepared tray.
With the barbecue set up for a baking (in-direct method) at a medium heat, place the tray on the cooking grate and cook for approximately 30 minutes, keeping the lid closed. To check when the brownies are ready, insert a knife and the blade should come out clean.
Allow to cool for 10 minutes and then sprinkle over the popping candy, and serve. Alternatively, incorporate the popping candy into some chocolate frosting and spread over the top of the brownie.