Preheat the oven to 350°F/180°C. Butter a 9x13-in. brownie pan.
Combine the caramel sauce and 3 Tbsp. of flour in a small bowl and set aside.
In a medium saucepan, melt together the unsweetened chocolate and butter over low heat, stirring continuously. Remove from the heat and cool slightly.
Add the sugars and mix to incorporate. Whisk in the eggs and vanilla and mix until smooth. Add the remaining 1 c. flour and salt and mix well.
Pour the batter into the prepared pan and spread into an even layer. Place the pan on the middle rack of the oven and bake for 20 minutes.
Remove the pan from the oven and pour the caramel mixture over the partially baked brownie layer. Return the pan to the oven for 5 minutes only, taking care not to overbake.
Remove the pan from the oven and immediately sprinkle the toasted pecans over the caramel layer. Transfer the brownies to a wire rack and cool.
In a small microwavable bowl, combine the bittersweet chocolate and heavy cream, and microwave on high for 35 - 40 seconds. Stir the mixture until it is smooth.
Transfer the chocolate mixture to a pastry bag or squeeze bottle and drizzle it over the top of the brownies. Slice the brownies and serve.
Recipe is included with our Kitchen Essentials from Calphalon 9x13-in. Brownie Pan.