Preheat your oven to 180C/160C Fan and line a 9″ square baking tray with parchment paper.
Melt together the butter, and dark chocolate in a heatproof bowl over a pan of boiling water, on the microwave for 1-2 minutes until melted. Leave to the side to cool to room temperature!
Using an electric whisk/stand mixer, whisk together the eggs & light brown sugar for a few minutes until the colour has turned pale, is very mousse like, and is double the original volume of the amount of eggs + sugar!
You will know its done because when you lift the whisk up out of the mix it should leave a trail for a couple of seconds before disappearing!
When whisked, pour the cooled chocolate mix over eggs and fold together carefully. It might take some time, but be patient – you don’t want to knock out the air you made up on the previous step!
Once completely combined, sift the cocoa powder and plain flour on top of the chocolate mix and then fold together again – still be careful to not knock out the air!
Once combined well, fold through the Kinder chocolate pieces, and the Kinder Bueno pieces and pour into the prepared tin – bake in the oven for 25-30 minutes! Once baked, leave to cool in the tin completely, and cut into your squares!
Notes
These brownies will last for up to one week in a container, but will probably be eaten before this!
You can easily use another sugar in the mix, such as caster sugar, but I thought I'd try light brown sugar this time and it was delicious!
If your brownies are taking ages to cook, your mixture was probably too thin in the beginning. Cover with foil and bake for longer.
If they still don't seem set after cooling, store them in the fridge and then cut so they're firmer.