01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until mixture reaches crumbly consistency. 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 granulated sugar, all-purpose flour, and salt together in a saucepan until thoroughly blended.
04 - Gradually whisk whole milk into the dry mixture, ensuring smooth incorporation before heating.
05 - Place saucepan over medium heat. Whisk continuously until mixture thickens and begins to bubble, approximately 4 to 5 minutes.
06 - Whisk egg yolks in a separate bowl. Slowly incorporate small amounts of the hot milk mixture while whisking constantly to warm eggs gently.
07 - Return tempered egg mixture to saucepan. Cook for 2 additional minutes while whisking until filling becomes thick and glossy.
08 - Remove from heat. Stir in unsalted butter and vanilla extract until completely smooth and incorporated.
09 - Pour warm filling over peanut butter crumbs in crust. Cool for 15 minutes at room temperature, then refrigerate for minimum 2 hours until fully set.
10 - Beat heavy whipping cream, powdered sugar, and vanilla extract using electric mixer until stiff peaks form.
11 - Spread whipped cream over chilled pie surface. Garnish by sprinkling remaining peanut butter crumbs atop before serving.