01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until crumbly texture forms. Reserve for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the baked and cooled pie crust.
03 - Whisk together granulated sugar, all-purpose flour, and salt in a saucepan until thoroughly blended.
04 - Gradually whisk whole milk into the dry mixture until smooth. Place saucepan over medium heat and cook, whisking constantly for 4-5 minutes until mixture thickens and just begins to boil.
05 - Whisk egg yolks in a separate bowl. Slowly incorporate a small amount of the hot milk mixture while whisking continuously to temper the eggs.
06 - Return the tempered egg mixture to the saucepan, whisking constantly. Cook for an additional 2 minutes until thickened and glossy. Remove from heat and stir in butter and vanilla extract until smooth.
07 - Pour the warm filling over the peanut butter crumbs in the pie shell. Let cool at room temperature for 15 minutes, then refrigerate for at least 2 hours until completely set.
08 - Beat heavy whipping cream, powdered sugar, and vanilla extract using an electric mixer until stiff peaks form. Spread the whipped cream evenly over the chilled pie surface.
09 - Sprinkle the remaining peanut butter crumbs over the whipped cream topping. Slice and serve chilled.