01 - Mix creamy peanut butter and powdered sugar in a medium bowl with a fork until crumbly. Set aside for later use.
02 - Spread half of the peanut butter crumbs evenly across the bottom of the baked pie crust.
03 - Whisk together granulated sugar, all-purpose flour, and salt in a saucepan until well blended.
04 - Gradually whisk in whole milk to the dry mixture, stirring until completely smooth and no lumps remain.
05 - Place saucepan over medium heat, whisking constantly until mixture thickens and just begins to boil, approximately 4–5 minutes.
06 - Whisk egg yolks in a separate bowl. Gradually incorporate a small amount of the hot milk mixture while whisking continuously to temper the eggs.
07 - Pour the tempered egg mixture back into the saucepan, whisking constantly. Cook for an additional 2 minutes until thick and glossy.
08 - Remove from heat. Stir in unsalted butter and vanilla extract until completely smooth and incorporated.
09 - Pour the warm filling over the peanut butter crumbs in the pie shell. Let cool for 15 minutes at room temperature, then refrigerate for at least 2 hours until fully set.
10 - Beat heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form. Spread the whipped cream evenly over the chilled pie surface.
11 - Sprinkle the remaining peanut butter crumbs generously over the whipped cream topping just before serving.