✓ Preheat oven to 350°F (175°C) and line a 9×13‑inch pan with parchment paper.

✓ Mix melted butter and brown sugar in a large bowl until glossy and sugar begins to dissolve.

✓ Beat in the egg and vanilla extract until fully incorporated.

✓ Sift flour, baking powder, and salt together, then fold into the wet mixture.

✓ Gently fold chopped pretzels into the batter.

✓ Spread the batter evenly in the prepared pan and smooth the surface.

✓ Bake for 20‑25 minutes until edges turn deep golden brown and a toothpick shows few moist crumbs.

✓ Remove from oven and let cool in the pan for 10 minutes.

✓ Warm the salted caramel sauce until pourable.

✓ Drizzle caramel over the warm bars in a zig‑zag pattern.

✓ Sprinkle flaky sea salt over the caramel immediately.

✓ Allow the bars to cool completely on a wire rack, about 45 minutes.

✓ Lift the parchment paper to release the slab, then cut into 24 bars.

✓ Serve at room temperature or refrigerate for up to 3 days.