Line a 13x9-in. pan with foil; grease foil with 2 teaspoons butter and set aside.
In a small saucepan, combine milk chocolate chips, butterscotch chips and peanut butter; stir over low heat until melted and smooth. Spread into prepared pan. Refrigerate until set.
For filling, in a small heavy saucepan, melt butter over medium heat. Add sugar and milk; bring to a gentle boil. Reduce heat to medium-low; cook and stir 5 minutes. Remove from heat; stir in marshmallow creme, peanut butter and vanilla until smooth. Add peanuts. Spread over first layer. Refrigerate until set.
For caramel layer, in a small heavy saucepan, combine caramels and cream; stir over low heat until melted and smooth. Spread over filling. Refrigerate until set.
In another saucepan, combine chips and peanut butter; stir over low heat until melted and smooth. Pour over the caramel layer. Refrigerate at least 1 hour.
Cut into 1-in.-wide strips, then into squares. Store in an airtight container.