Heat oven to 350°. Line a 13x9" pan with parchment or non-stick foil. In large bowl, stir peanut butter cookie dough ingredients until soft dough forms. Press dough in bottom of pan. Bake 12-15 min. or until light golden brown. Cool completely, about 30 min.
In large bowl, beat all the filling ingredients except powdered sugar with electric mixer on medium speed until creamy. Gradually beat in powdered sugar until well blended. This will be very thick. Press filling over cookie layer. Refrigerate.
In 2-quart saucepan, heat caramels and 2TB of water over low heat, stirring constantly until caramels are melted. (You can also do this step in the microwave. Cook 1min on high and then stir and keep checking every 30sec until smooth.) Stir in peanuts. Spread evenly over filling. Refrigerate about 15min or until caramel layer is firm.
In small microwavable bowl, microwave chocolate chips uncovered on high 1-2min, stirring once, until melted. Spread evenly over caramel layer. Refrigerate ~1hr or until chocolate is set. Cut to desired size.(I usually cut them into 1" squares) Store covered at room temp or in refrigerator or freezer.