Whisk together the granulated sugar, egg yolks, cornstarch, salt and 1/3 cup of the milk in a large bowl.
Heat the remaining 2 2/3 cups milk in a large saucepan over medium heat until hot but not boiling.
Whisk half of the hot milk into the egg mixture until smooth, and then gradually whisk the egg mixture into the saucepan with the remaining milk. Bring to a boil, whisking constantly, and cook, continuing to whisk, until the mixture thickens, 6 to 8 minutes.
Remove from the heat and whisk in the peanut butter until melted.
Transfer to a bowl and let cool slightly, stirring a few times to prevent a skin from forming.
Pour the filling into the crust, smoothing it out so that it reaches the edges of the pie crust. Press plastic wrap directly onto the surface and chill until set, at least 4 hours.
When ready to serve, whip the cream and confectioners' sugar in a large mixing bowl with a hand mixer until medium/stiff peaks form.
To assemble, top the pie with the whipped cream and garnish with the peanuts and chocolate chips.
