Prep the pan and oven. Heat the oven to 350°F (175°C). Line a 9x13-inch pan with parchment, leaving overhang for easy lifting. Lightly grease the parchment.

Melt the butter. In a saucepan over low heat, melt the butter until just liquid. Let it cool for 3–4 minutes so it doesn’t scramble the eggs later.

Whisk the sugars and eggs. In a large bowl, whisk granulated sugar, brown sugar, and eggs for about 1 minute until slightly thick and glossy. Add vanilla and whisk again. This step gives your brownies that shiny top.

Add the butter. Slowly stream in the cooled melted butter while whisking. Mix until smooth and combined.

Combine the dry ingredients. In a separate bowl, whisk flour, cocoa powder, fine sea salt, and baking powder. If using espresso powder, add it here.

Make the batter. Fold the dry ingredients into the wet mixture using a spatula. Stop when you have no visible dry streaks. Stir in chocolate chips.

Layer with pretzels. Spread half the brownie batter into the pan. Sprinkle with about half the crushed pretzels, pressing them lightly so they stick.

Add caramel. Drizzle about half the caramel sauce over the pretzels. Use a butter knife to gently swirl it into the batter. Don’t overmix—distinct ribbons are best.

Top and swirl again. Spread the remaining batter over the top. Add the rest of the caramel in lines or dollops and swirl again. Scatter the remaining pretzels on top, then finish with a pinch of flaky salt.

Bake. Bake for 26–32 minutes, depending on your oven. Look for set edges and a center that jiggles slightly but doesn’t look wet. A toothpick should come out with a few moist crumbs, not raw batter.

Cool before slicing. Let the pan cool on a rack for at least 45–60 minutes. For extra clean slices, chill in the fridge for 30 minutes before cutting.

Serve. Cut into squares. Add a final sprinkle of flaky salt if you like. Warm and gooey is amazing, but room temperature gives the neatest cuts and best texture balance.