Preheat your oven to 170°C

Melt the butter and chocolate together. Set aside to cool.

With an electric whisk, whisk the sugar and eggs together until thick and doubled in size.

Pour the egg mixture into the chocolate mixture and stir.

Sieve the cocoa powder and flour into the mixture and stir until just combined.

Add in the chocolate chips and stir again.

Pour into your greased and lined square brownie tin, and cook in the oven at 170 for 25-30 minutes depending on how gooey you want the brownies.

Take out of the oven, leave to cool completely before slicing.