01 - Set oven to 350°F (175°C) and line a 9x13-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large bowl, melt butter then whisk in both granulated sugar and light brown sugar until smooth.
03 - Incorporate eggs one at a time, mixing well after each addition, then blend in vanilla extract.
04 - Sift together all-purpose flour, cocoa powder, and salt; gradually fold into wet mixture until just combined.
05 - Spread half the brownie batter into prepared pan, then arrange mini salted pretzels evenly across the top.
06 - Combine soft caramel candies with heavy cream and sea salt in a small saucepan; melt over low heat, stirring constantly until pourable.
07 - Pour the melted caramel sauce over pretzel layer, gently smooth out with spatula.
08 - Scatter chocolate chips over caramel, then carefully spread remaining brownie batter to cover.
09 - Place pan in preheated oven and bake for 28-32 minutes, or until a toothpick inserted comes out with few moist crumbs.
10 - Sprinkle additional pretzels and sea salt flakes while warm; allow to cool completely in pan before cutting into squares.