Prepare the Pie Crust: Ensure the pie crust is pre-baked and completely cooled. If using a store-bought crust, follow the package instructions for baking.
Make the Peanut Butter Mixture: In a medium bowl, combine the creamy peanut butter and powdered sugar. Mix until the texture becomes crumbly.
Whip the Heavy Cream: In a separate bowl, whip the heavy cream and vanilla extract until stiff peaks form. Use a hand mixer or stand mixer for the best results.
Prepare the Cream Cheese Mixture: In another bowl, beat the softened cream cheese until smooth. Gradually add the milk, mixing until fully incorporated and creamy.
Combine the Layers: Gently fold the whipped cream into the cream cheese mixture until evenly combined. Add the peanut butter crumbles and stir gently to create the filling.
Assemble the Pie: Spoon the filling into the cooled pie crust and smooth the top with a spatula.
Chill: Refrigerate the pie for at least 4 hours, or preferably overnight, to allow the filling to set.
Garnish and Serve: Top the pie with whipped cream and sprinkle with chopped peanuts if desired. Slice and serve chilled.