Preheat the oven to 180ºc/160fan and grease 2-3 doughnut moulds (the recipe makes 15-18 bronuts) - place the prepped moulds on baking trays.
Add the dark chocolate and unsalted butter to a bowl, and melt together until smooth - I do this in the microwave.
Once melted, leave this to cool for 10 minutes.
In a new bowl, add the eggs and light brown soft sugar and whisk together for a few minutes - the mixture should double in volume, be lighter in colour and mousse like.
Once whipped, pour in the cooled chocolate mixture and carefully fold together.
Add in the plain flour and cocoa powder and fold together again.
Finally, add in the chocolate chips and fold through.
Add the brownie mixture to a large piping bag, and pipe into the prepared doughnut moulds.
Bake the bronuts in the oven for 16-18 minutes - once baked, leave to cool fully, in the moulds.
Decoration
Once the bronuts have cooled, melt the two chocolates in separate bowls (that are big enough to dunk the bronuts into).
Dunk half of the bronuts into the white chocolate, and half into the milk chocolate, placing each onto a lined tray.
With the leftover chocolate, drizzle on any decoration like I have.
Add a flake, sprinkles or whatever you fancy to each bronut and let the chocolate set. Enjoy!