Heat oven to 450°F. Bake pie crust as directed on box for One-Crust Baked Shell, using 10-inch glass pie plate. Cool completely on cooling rack, about 15 minutes.
Meanwhile, in medium microwavable bowl, microwave caramels and milk uncovered on High 1 to 2 minutes or until melted; stir until smooth. Reserve 2 tablespoons melted caramel. Stir 1 1/2 cups peanuts into remaining caramel. Pour caramel mixture into baked pie crust.
Reduce oven temperature to 350°F. In large bowl, stir condensed milk, egg and peanut butter until smooth. Stir in chopped peanut butter cups. Pour in crust over caramel mixture. Bake 30 to 35 minutes or until filling is set. Refrigerate 1 hour. Drizzle melted candy bar and reserved caramel over top of pie. Sprinkle with 1/4 cup peanuts. Lightly sprinkle with kosher salt. Cover and refrigerate any remaining pie.