Preheat oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper.
Whisk melted butter, granulated sugar, and brown sugar until smooth.
Add eggs and vanilla and whisk until glossy.
Stir in cocoa powder, flour, and salt until just combined.
Fold in chocolate chips and half of the crushed pretzels.
Spread batter evenly into prepared pan.
Drizzle caramel sauce over batter and swirl lightly with a knife.
Sprinkle remaining pretzels and a pinch of flaky sea salt on top.
Bake 28–32 minutes until center is set but slightly fudgy.
Cool completely before slicing into squares.
