Preheat your oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, allowing some overhang on the sides for easy removal later.
In a double boiler or a microwave-safe bowl, combine the unsweetened baking chocolate, 3 ounces (85g) of the semi-sweet chocolate, and 10 tablespoons (140g) of unsalted butter. Heat gently until melted and smooth, stirring occasionally. Remove from heat and let cool slightly.
In a large mixing bowl, combine the granulated sugar, eggs, and vanilla extract. Whisk together until well combined. Gradually add the melted chocolate mixture, stirring until everything is incorporated.
In a separate bowl, whisk together the unsweetened cocoa powder, all-purpose flour, and salt. Gradually add this dry mixture to the wet ingredients, folding gently with a spatula until just combined.
Fold in the chopped pecans and ¾ cup (90g) of caramel bits, making sure they are evenly distributed throughout the brownie batter.
Pour the brownie batter into the prepared pan, smoothing the top with a spatula. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
While the brownies are baking, combine the remaining 2 ounces (60g) of semi-sweet chocolate, the remaining ¼ cup (30g) of caramel bits, and 2 teaspoons of milk in a small saucepan over low heat. Stir until melted and smooth.
Once the brownies are out of the oven, immediately drizzle the melted chocolate-caramel mixture over the top. Use a spatula to spread it evenly, and then top with the pecan halves for garnish.
Let the brownies cool in the pan for at least 15 minutes before using the parchment overhang to lift them out onto a cutting board. Slice into squares and enjoy!