Let cookie dough hang out at room temp for about 10 minutes to soften. In a large bowl, combine dough and chopped trail mix bars. Press into an ungreased 9x13 inch baking pan. Bake uncovered at 350 for 10-12 minutes.
Sprinkle with butterscotch chips and marshmallows. Bake 3-4 minutes longer until marshmallows begin to brown. Sprinkle with walnuts; arrange pretzels over the top.
In a small sauce pan melt the peanut butter chips, corn syrup, and butter; spoon over bars evenly.
In a microwave, melt chocolate chips, stirring every few seconds to avoid burning! Stir until smooth. Spread over bars, and refrigerate for 1 hour or until chocolate is set. Cut and serve!
You could really customize these to your liking. Swap walnuts for peanuts, or omit nuts. Throw in mini M&Ms if you're not into butterscotch. I love to use dark chocolate chips for the top because it is my favorite!