Step 1

Bake the crust for a filled pie according to the package instructions and cool completely.

Step 2

Preheat the oven to 325°F. In a small bowl, use a fork to mix the powdered sugar and the peanut butter together until it is crumbly. Spread about half of the peanut butter mixture in the bottom of the cooled pie crust. Set the other aside.

Step 3

In a medium saucepan, whisk together the cornstarch, 2/3 cup sugar, and salt. Add the egg yolks and milk and whisk well. Heat over medium low heat, stirring constantly to prevent scorching, until thickened - about 10 minutes. The mixture should be the consistently of thick pudding. Remove from the heat and add the vanilla and butter. Stir until the butter has melted. Pour the mixture over the peanut butter mixture in the bottom of the pie crust.

Step 4

Make the meringue by beating the egg whites in a clean bowl until frothy. Gradually add the other 1/4 cup sugar and continue to beat until you get to the stiff peak stage. The time to get there varies based on the mixer you're using. The meringue should be glossy. Spread over the custard filling in the pie. Sprinkle the remaining peanut butter crumble mixture over the meringue and bake for 20 to 30 minutes or until golden brown. Cool completely and then chill in the refrigerator for 2 to 4 hours or overnight before serving.