MAKE THE CRUST:

1. PREP: Heat oven to 350 degrees F. Line a 9-inch square baking pan with parchment paper leaving a 2-inch overhang on two sides.
2. MAKE PRETZEL BASE: In the bowl of a food processor, combine pretzels and sugar and process until you have fine crumbs. Add the melted butter and process until evenly moistened.
3. BAKE: Transfer the mixture to the prepared pan and press down into a compact, even layer. Bake until crust is fragrant and edges are browned, about 15-17 minutes. Sprinkle with pecans and set aside until ready to use. 

FOR THE SALTED CARAMEL:

1.  MAKE THE SAUCE: In a medium saucepan, combine butter, cream, brown sugar and salt. Heat mixture over medium heat, stirring, until butter melts until combined. Turn heat to medium-high, and bring to a simmer. Cook for 2 minutes.
2. POUR OVER CRUST: Pour over the prepared crust.
3. BAKE: Place in oven and bake until caramel is bubbling and has darkened slightly, 13-15 minutes.
4. COOL: Transfer to a rack to cool.

FOR THE TOP:

1. MELT THE CHOCOLATE: While the caramel is cooling, melt chocolate over a pot of simmering water (in a heatproof bowl in a microwave).
2. ADD THE BARS: Let chocolate cool for a few minutes, then spread evenly over slightly cooled caramel. Carefully spread the chocolate over the top of the caramel.
3. TOP WITH PRETZELS: Sprinkle with crushed pretzels and then let cool to room temperature.
4. COOL: Transfer to the refrigerator to set for 30 to 60 minutes.
5. SERVE & STORE: To serve, lift the bars out of the pan using the parchment overhang as handles. Then transfer to a cutting board and cut into 16 or 20 squares. Store in an airtight container in the refrigerator.