For the brownies:
1 cup (2 sticks) butter
12 ounces bittersweet or semisweet chocolate, coarsely chopped
1½ cups sugar
4 large eggs
1 tablespoon vanilla extract
1¼ cups all-purpose flour
½ teaspoon salt
1½ cups pecans, coarsely chopped (optional, I didn’t use any)
1 cup semisweet chocolate chips
For the caramel filling:
14 ounces caramel candies, unwrapped
1/4 cup heavy cream
Preheat the oven to 350˚ F. Line a 9×13-inch baking pan with foil and grease the foil well with butter or cooking spray. In a large, microwave-safe bowl, combine the chopped chocolate and butter. Microwave in intervals of 1 minute at 50% power until the chocolate is melted and the mixture is smooth, stirring in between intervals. Whisk in the sugar, eggs and vanilla until incorporated. Stir in the flour and salt just until combined. Spread about half of the brownie batter in the bottom of the prepared pan in an even layer. Bake for 18 minutes. Remove from the oven (keep the oven on!) and let the brownies cool for 20 minutes.
Meanwhile, add the chopped pecans (if using) to a medium skillet over medium heat. Toast, stirring occasionally, until fragrant and light golden brown. Remove from the heat and set aside. To make the caramel filling, combine the caramels and cream in a medium microwave-safe bowl. Microwave for 30 seconds at 50% power. Stir. Repeat the process, keeping a close eye on the mixture as it can burn very easily (make sure you use low heat in the microwave). Continue the microwave process until the caramels and cream are melted and combined. Stir in half of the pecans to the caramel mixture. Immediately spread the caramel mixture over the bottom brownie layer. Scoop the remaining brownie batter in spoonfuls over the caramel layer and spread it evenly across the caramel layer (spooning the batter in piles over the caramel will help to get an even layer of batter over the caramel). Sprinkle the chocolate chips and the remaining pecans on top of the final brownie layer. Bake for 20 minutes. Transfer to a wire rack and let cool completely before slicing and serving. I found the brownies sliced easier once they had been cooled and refrigerated for an hour or two.
Lift the brownies from the pan using the edges of the foil. Remove the foil and cut the brownies into individual squares. Store in an airtight container.