Preheat your oven to 350 degrees and spray a 9 x 13 baking dish with non-stick spray. Set aside.
In a large bowl, add the cake mix, egg, butter, and milk, and beat on medium until it comes together into a thick batter. Divide the batter in half and move half to a separate small bowl - put this bowl into the fridge until you're ready to work with it.
In the half of the batter that's still in your mixing bowl, pour in the broken pretzels and mix on low until distributed.
Press the batter until your prepared baking dish. [If your batter is too sticky to press down, put it into the freezer for a few minutes - it'll be much easier to work with!]
Bake for 8-9 minutes - the batter should just barely be set.
While the bottom layer is baking, in a large bowl, add the other egg, peanut butter, cream cheese, and powdered sugar and beat until smooth and creamy.
Once the bottom layer is done, carefully (the pan is hot!) spread the peanut butter layer on top.
Sprinkle on the caramel bits then the chocolate chips.
Remove the remaining batter from the fridge and flatten it into small pieces and evenly over the top.
Bake for 18-20 minutes until the cake batter is puffy and golden.
Remove from the oven and let cool before slicing into bars.