01 - In a medium bowl, mix together the peanut butter and powdered sugar with a fork until crumbly. Set aside.
02 - Spread half of the peanut butter crumbs in the bottom of the baked pie crust.
03 - In a saucepan, whisk together granulated sugar, flour, and salt. Gradually whisk in milk until smooth.
04 - Place the saucepan over medium heat. Cook, whisking constantly until mixture thickens and just begins to boil (about 4-5 minutes).
05 - In a separate bowl, whisk the egg yolks. Gradually whisk in a little of the hot milk mixture to temper the eggs.
06 - Slowly pour the egg mixture back into the saucepan, whisking constantly. Cook for another 2 minutes until thick and glossy.
07 - Remove from heat. Stir in butter and vanilla until smooth.
08 - Pour the filling over the peanut butter crumbs in the pie shell. Allow to cool for about 15 minutes, then refrigerate for at least 2 hours until completely set.
09 - Beat the heavy cream, powdered sugar, and vanilla until stiff peaks form. Spread over chilled pie.
10 - Sprinkle with the remaining peanut butter crumbs before serving.