Preheat oven to 150 degrees Celsius.
Melt together chocolate bar, butter and salt. Set aside to cool.
Beat eggs in a stand mixer with paddle attachment for 6 minutes or until the eggs turned out light yellow.
Gradually add sugar while mixing. Scrape of the side of the mixing bowl and mix again for 2 minutes.
Fold in the melted chocolate mixture using a spatula.
Sift flour and add fold into the mixture.
Fold the vanilla extract and chocolate chips into the batter.
Bake for 35 - 45 minutes or until a toothpick comes out with tiny bits of most brownie.
Cool completely before cutting.
