Preheat oven 180C, line the pan with baking paper/foil.
Melt dark chocolate in microwave at high heat for 30 secsIn a large bowl, mix melted butter, sugar and a pinch of salt together.
Put two eggs and vanilla extract into the bowl, mix well.
Add the melted dark chocolate into the mix, whisk until well combine.
Sift flour and cocoa powder into the bowl, mix well.
Spread the brownie mix into the pan.
Bake at 180°C for 10 mins.
Once cooked, remove the brownie from the pan.
Cool completely on cooling rack (about 30 mins).