Preheat the oven to 170 degrees celsius and line a 9" square baking tray with greaseproof paper.
In a large bowl, whisk together the melted butter, sugar, vanilla, eggs and egg yolk until well combined.
Melt the 113g dark chocolate and mix into the butter mixture until fully mixed.
Fold in the flour, cocoa powder and salt to the mixture and mix until just combined a smooth brownie mixture made.
Fold in the chocolate chips to the mixture until evenly distributed.
Pour the mixture into the prepared tin and spread evenly. Pour the pecan mixture on top ensuring the pecans are evenly around the brownie. Note: It's ok there is lots of caramel liquid, it will solidify once baked.
Place in the preheated oven and bake for 25-30 minutes until a crispy skin forms but is still soft and gooey on the inside. The key is to underbake slightly to make sure you haven't got a dry brownie!
Leave to cool on a wire rack and cut up into 12 pieces.