Preheat oven to 350 degrees F. Line a 13x9x2-inch baking pan with heavy foil (or parchment paper), extending foil over the edges of the pan; set pan aside.
In a large bowl, beat butter with an electric mixer on medium speed for 30 seconds, until fluffy. Add brown sugar, egg yolks, and vanilla. Beat until combined, scraping bowl occasionally if needed.
In a mixing bowl, combine flour, crushed pretzels, baking powder, and baking soda. Beat in flour mixture. If mixture gets too thick for your mixer to handle, use a wooden spoon to incorporate all the flour. Press mixture evenly into the bottom of the prepared pan. Spray the bottom of a measuring cup with non-stick cooking spray and use it to pack the mixture down into that even layer.
Bake in the preheated oven for 12 to 14 minutes or until lightly browned.
While the base layer is baking, in a medium microwave-safe bowl, combine marshmallow creme and peanut butter. Microwave for 1 minute or until softened and slightly melted, stopping to stir after 30 seconds. Stir in powdered sugar. Spread mixture over warm crust.
Sprinkle with salted peanuts.
To another microwave-safe bowl, add unwrapped caramels and heavy cream. Stir to coat the caramels in cream, then microwave, 30 seconds at a time, stirring after each 30 seconds, until melted and smooth. Pour caramel mixture evenly over peanut layer.
Cool in pan on wire rack. Using the foil, lift the uncut bars out of the pan. Cut into bars or into bite-sized pieces. Makes 48 bars 3.0”x0.75” in size.