01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until crumbly texture forms. Reserve mixture for later use.
02 - Press half of the prepared peanut butter crumbs evenly into the bottom of the cooled baked pie crust.
03 - Whisk together granulated sugar, all-purpose flour, and salt in a saucepan until thoroughly blended.
04 - Gradually whisk in whole milk to the dry mixture, stirring continuously until completely smooth and no lumps remain.
05 - Place saucepan over medium heat, whisking constantly until mixture thickens and begins to bubble, approximately 4 to 5 minutes.
06 - Whisk egg yolks in a separate bowl. Slowly incorporate a small amount of the hot milk mixture while whisking vigorously to warm the eggs gradually.
07 - Return tempered egg mixture to the saucepan, whisking continuously. Cook for 2 minutes until mixture achieves thick, glossy consistency.
08 - Remove from heat immediately. Stir in unsalted butter and vanilla extract until fully incorporated and smooth.
09 - Pour hot filling evenly over the peanut butter crumb layer in the crust. Allow to cool at room temperature for 15 minutes.
10 - Transfer pie to refrigerator and chill for minimum 2 hours until filling is completely set and firm.
11 - Beat heavy whipping cream with powdered sugar and vanilla extract using electric mixer until stiff peaks form.
12 - Spread whipped cream evenly over chilled pie surface. Sprinkle remaining peanut butter crumbs across top before serving.