Preheat the oven to 350 degrees F. Line a 13×9 inch metal pan with nonstick foil.In a large saucepan, melt the butter. Reduce heat to low and add both chocolates. Stir on the lowest heat possible until chocolate is melted and smooth.
Remove from heat and let cool to lukewarm.Stir in the sugar, vanilla and add the eggs, 1 at a time, stirring well after each addition. Stir in the salt and the flour, stirring unitl the mixture is just combined.
Add the chocolate chips (make sure mixture is completely cool before doing this).
Pour the batter in the pan. Smooth the top and bake on center rack for 28 to 32 minutes or until brownies appear set.
Let cool completely on a pan set on a wire rack. For neater slicing, chill brownies.
