Pre-heat your oven to 170℃ Fan/385℉. Line a 9x13" Sheet Pan with greaseproof paper.
In a small bowl, break up the dark/semi-sweet chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn. Alternatively, set up a double boiler. Do this by placing a heatproof bowl over a small pot of simmering water. Add the chocolate to the heatproof bowl and stir until melted.
In a large mixing bowl, whisk together melted butter and both sugars. With an electric/stand mixer, go for a solid 3-5minutes so it is totally combined. Add in the eggs, one at a time and mixing in between. Add the vanilla and mix again.
Now, add the chocolate slowly and combine once again.
Add the flour and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Fold in the chocolate chips.
Pour the batter into the lined pan and bake approx 20-25 minutes. Remove pan when the middle is still just slightly wobbly. Let cool.
Optional: Melt about 25g white chocolate and drizzle over the brownies!
