Preheat your 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, combine the melted butter and granulated sugar. Stir well until fully combined. Add the eggs one at a time, mixing thoroughly after each addition. Then, mix in the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Avoid overmixing to keep the brownies fudgy.
Gently fold in the chocolate chips and chopped pretzels into the brownie batter.
Pour half of the brownie batter into the prepared baking pan, spreading it evenly. Drizzle half of the caramel sauce over the batter, then add the remaining brownie batter on top, smoothing it out. Drizzle the remaining caramel sauce over the top layer of brownie batter and sprinkle with extra chopped pretzels.
Before placing it in the oven, lightly sprinkle sea salt flakes on top of the caramel layer.
Bake the brownies in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 20 minutes before transferring them to a wire rack to cool completely. Cut into squares for serving.
Notes
For best results, let the brownies cool completely before cutting.