2. 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; boil and stir for 5 minutes. Remove from the heat; stir in the marshmallow creme, peanut butter and vanilla. Add peanuts. Spread over first layer. Refrigerate until set.
3. For the caramel layer, in a small heavy saucepan, combine caramels and cream; stir over low heat until melted and smooth. Cook and stir 4 minutes longer. Spread over the filling. Refrigerate until set.