For the caramel sauce

1. Prepare according to caramel sauce recipe.
2. Allow to cool for 10-15 minutes.

For the brownies

1. While caramel is cooling, preheat oven to 350°F/177°C.  Line an 8x8-inch square pan with parchment paper and set aside.
2. Place the butter and chopped chocolate into a medium heatproof bowl set over a small saucepan filled with an inch of simmering water.  Whisk until mixture is completely melted and smooth.  Remove bowl from heat and add sugar to the mixture whisking vigorously until combined.  Set aside to cool slightly.
3. Add eggs and vanilla to chocolate mixture.  Whisk until well combined, about 1 minute.
4. Using a rubber spatula, fold in cocoa powder, flour and salt until just combined.  Do not over mix.
5. Pour 2/3 of the brownie batter into prepared pan and smooth.  Pour 3/4 of the caramel over the brownie batter allowing for a 1/2" border.  Carefully pour the remaining batter over the caramel and spread with an offset spatula (it's ok for the caramel to seep out of the boarder).
6. Bake in preheated oven for 24 to 28 minutes, or until a toothpick inserted in the center comes out mostly clean with some moist crumbs.  Allow to completely cool in pan before slicing.  Drizzle with remaining caramel if desired.