01 - In a medium bowl, combine creamy peanut butter and powdered sugar. Mix with a fork until mixture reaches a crumbly consistency. Set aside for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the baked and cooled 9-inch pie crust. Press gently to create an even layer.
03 - In a medium saucepan, whisk together granulated sugar, all-purpose flour, and salt until thoroughly blended. Ensure no lumps remain in the mixture.
04 - Gradually whisk whole milk into the dry ingredients until smooth. Place saucepan over medium heat and cook, whisking constantly, until mixture thickens and begins to bubble, approximately 4-5 minutes.
05 - While mixture heats, whisk egg yolks in a separate bowl. Carefully whisk a small amount (about 1/4 cup) of the hot milk mixture into the yolks to gradually raise their temperature without scrambling.
06 - Slowly pour the warmed egg mixture back into the saucepan, whisking continuously. Continue cooking for 2 additional minutes until filling becomes thick and glossy. Remove from heat.
07 - Stir unsalted butter and vanilla extract into the hot filling until butter melts completely and mixture is smooth and velvety.
08 - Pour the warm filling over the peanut butter crumb layer in the pie crust. Let cool at room temperature for 15 minutes, then refrigerate for at least 2 hours until completely set and firm.
09 - In a chilled bowl, beat heavy whipping cream with powdered sugar and vanilla extract using an electric mixer until stiff peaks form. Do not overbeat.
10 - Spread whipped cream evenly over the chilled pie surface. Sprinkle remaining peanut butter crumbs generously across the top before serving. Slice and serve chilled.