Preheat the oven to 180ºc/160ºc fan and line an 8” round cake tin
Melt the butter and dark chocolate together and cool - I use the microwave but you can use a bowl over a pan of simmering water
Add the eggs, egg yolk and sugar to a bowl and whisk until thick - this can take a few minutes
Fold through the butter/chocolate mix carefully into the eggs and sugar
Then, fold through the flour and cocoa
Finally, fold through the chocolate chips/chunks
Pour into the tin and bake for 20-25 minutes until there is a slight wobble in the middle and leave in the tin to cool fully
Preferably, set the brownies in the fridge for a few hours
Decoration
Beat the butter on it’s own until light in colour
Add the icing sugar and vanilla and mix again
Remove a third and keep this as white
Colour the last two thirds with the extra strong red colouring (see blog post notes about this if needed)
Cut the brownie into 8 sections
Pipe the buttercream onto the brownie - I do the star at the top in white first, fill the middle with the red, and then finish the bottom with the white
Notes
These brownies will last for 4-5+ days easily, in a cool place at room temperature or in the fridge.