Step 1: Prepare the Crust

1. If using a homemade pie crust, roll it out, fit it into a 9-inch pie pan, and bake according to your recipe instructions. Allow it to cool completely before filling.

Step 2: Make the Peanut Butter Crumbles

1. In a small bowl, mix the peanut butter and powdered sugar with a fork until crumbly. Set aside.

Step 3: Prepare the Custard Filling

1. In a medium saucepan, whisk together the cornstarch, granulated sugar, and a pinch of salt.
2. Gradually add the milk and heavy cream, whisking to combine. Heat the mixture over medium heat, stirring constantly, until it begins to thicken.
3. In a separate bowl, whisk the egg yolks. Slowly add a ladleful of the hot milk mixture to the yolks while whisking to temper them.
4. Pour the tempered yolks back into the saucepan and continue to cook over medium-low heat, stirring constantly, until the custard thickens and coats the back of a spoon.
5. Remove from heat and stir in the peanut butter and vanilla extract until smooth. Allow the custard to cool slightly.

Step 4: Assemble the Pie

1. Spread half of the peanut butter crumbles over the cooled pie crust.
2. Pour the peanut butter custard filling over the crumbles, smoothing the top with a spatula.
3. Cover the pie with plastic wrap, pressing it directly onto the surface of the filling to prevent a skin from forming. Refrigerate for at least 4 hours or until fully set.

Step 5: Whip the Cream Topping

1. In a chilled bowl, beat the heavy whipping cream and powdered sugar with an electric mixer until soft peaks form.

Step 6: Decorate and Serve

1. Spread or pipe the whipped cream over the chilled pie.
2. Garnish with the remaining peanut butter crumbles, chopped peanuts, or a drizzle of melted chocolate, if desired.
3. Slice and serve chilled.