1. Preheat oven to 180°C (350°F). Line a 20×20 cm (8×8-inch) baking pan with parchment paper.

2. For the pretzel bottom, crush the pretzels using a food processor or by hand in a zip-top bag with a rolling pin.

3. In a bowl, mix crushed pretzels with granulated sugar and melted butter until evenly moistened.

4. Press the pretzel mixture firmly into the bottom of the prepared pan. Refrigerate while making brownie batter.

5. To make the brownie layer, melt the butter in a saucepan. Remove from heat and stir in 200 grams chopped dark chocolate until melted and smooth. Let cool.

6. In a bowl, whisk together flour, sifted cocoa powder, and salt.

7. In a separate bowl, use an electric mixer to whisk eggs, granulated sugar, brown sugar, and vanilla on high speed for 5 minutes until pale and fluffy.

8. Pour in the cooled chocolate mixture and beat for 1 minute until combined.

9. Fold in the dry ingredients using a rubber spatula until just incorporated. Fold in optional chopped chocolate if using.

10. Remove the pan from the fridge and spread brownie batter evenly over the pretzel crust.

11. Bake for 20–30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Do not overbake.

12. Let the brownies cool slightly while making the caramel.

13. To make caramel, heat granulated sugar in a medium saucepan over medium heat, stirring constantly until melted.

14. Once melted, carefully add butter and whisk until fully combined and melted. The mixture will bubble up.

15. Slowly add the heavy cream while whisking, and let the caramel boil for 1–2 minutes.

16. Cool the caramel for about 5 minutes, then pour over the brownie layer in an even layer.

17. Allow the brownies to cool completely for 6–7 hours, preferably overnight.

18. Once set, sprinkle with flaky sea salt if desired, slice, and serve.