For the crust: Combine 1.5 cups finely crushed pretzels, 0.25 cup sugar, and 6 tablespoons melted butter in a 9-inch pie pan. Mix well and press firmly into the pan. Bake in a 350°F oven for 7 to 10 minutes. Set on a cooling rack and cool completely.
For the chocolate layer: In a small saucepan, bring 0.25 cup heavy cream to a simmer. Once simmering, remove from heat, add 1 cup milk chocolate chips and 1 tablespoon light corn syrup. Cover and let sit for about 2 minutes. Whisk until smooth and glossy. Pour over the cooled crust and refrigerate until set.
For the caramel layer: In a small saucepan, combine 0.67 cup butter, 0.5 cup brown sugar, 1 tablespoon light corn syrup, and 0.25 cup heavy cream. Stirring constantly, bring to a boil and cook for 2 minutes. Cool to almost room temperature and pour over the chocolate layer. Reserve about 2 tablespoons of caramel sauce to drizzle over the top.
For the peanut butter layer: In a large mixing bowl, beat 8 oz cream cheese until fluffy. Add 1.5 cups peanut butter, 2 teaspoons vanilla extract, 1 tablespoon butter, and 1.75 cups powdered sugar. Beat until well blended and fluffy. In another large mixing bowl, beat 2 cups whipping cream until stiff peaks form. Fold the whipped cream into the peanut butter mixture. Pour over the caramel layer.
For the topping: Drizzle the reserved caramel sauce over the top of the pie. Then, drizzle 3 tablespoons of melted peanut butter and sprinkle with 3 tablespoons of chopped milk chocolate chips. Place in the freezer and freeze for 3 to 5 hours before serving.
Notes
This pie is best made the day before you plan to serve it to allow it to freeze completely.