Preheat the oven to 350°F. Line an 8-inch square baking pan with parchment paper.
In a large bowl, stir together the cake mix, melted butter, and egg until a thick dough forms. Fold in the crushed pretzels and pecans.
Press the dough evenly into the prepared pan.
Bake for 18 to 22 minutes or until lightly golden around the edges. Let cool completely.
Place the caramel bits and heavy cream in a microwave-safe bowl. Microwave in 30-second intervals, stirring after each, until smooth. Stir in the flaky sea salt.
Pour the caramel over the cooled crust and spread into an even layer. Refrigerate for 20 minutes.
Beat the peanut butter, cream cheese, powdered sugar, and vanilla until smooth and fluffy.
Carefully spread the peanut butter mixture over the caramel layer. Refrigerate for another 20 minutes.
Melt the chocolate chips and butter together until smooth.
Stir in the crispy rice cereal and crushed potato chips until evenly coated.
Spread the chocolate crunch mixture over the peanut butter layer and gently smooth the top.
Refrigerate for about an hour or until firm.
Lift the bars from the pan, slice into squares, and serve.