Preheat the oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper.
In a heatproof bowl, melt the butter and Ghirardelli bittersweet chocolate together over a double boiler or in the microwave, stirring until smooth.
Whisk in the granulated sugar and brown sugar until fully combined.
Add the eggs and vanilla extract, mixing until smooth and glossy.
Sift in the flour, cocoa powder, and salt, folding gently until just combined.
Pour half of the brownie batter into the prepared pan and spread evenly.
Drizzle the caramel sauce over the batter, then top with the remaining brownie batter, spreading carefully to cover the caramel.
Swirl the caramel into the top layer with a knife or skewer.
Bake for 30-35 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
Let the brownies cool completely before slicing. Drizzle with additional caramel sauce before serving if desired.