Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking pan or line it with parchment paper for easy removal.
In a large mixing bowl, whisk together the melted butter and granulated sugar until well combined and smooth.
Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, sift together the flour, cocoa powder, and salt. Gradually add this dry mixture to the butter-sugar mixture, stirring until just combined.
Fold in the chocolate chips and chopped pecans, reserving a handful of pecans for topping.
Pour half of the brownie batter into the prepared baking pan, spreading it evenly.
Drizzle half of the caramel sauce over the brownie batter, then lightly swirl it with a knife to create a marbled effect.
Pour the remaining brownie batter over the caramel layer and spread it evenly. Drizzle the remaining caramel sauce on top and swirl again to combine slightly.
Sprinkle the reserved pecans and a pinch of sea salt (if desired) over the top.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out with moist crumbs (not wet batter).
Allow the brownies to cool in the pan for at least 30 minutes before cutting them into squares.
Notes
Serve warm with extra caramel sauce and vanilla ice cream.