In a saucepan, combine sugar, cornstarch and salt. Using a whisk, gradually stir in milk and cream. Whisk well to avoid lumps in pudding. Bring to a boil over medium heat. Cook and stir for 4-5 minutes after boiling begins. Do not allow pudding to burn. You must stir constantly.
Remove from the heat. Stir in peanut butter and vanilla. Mix until smooth. Pour into prepared pie crust. Top with whipped cream. Garnish with chopped peanuts, chocolate sprinkles, or a light sprinkle of cocoa if desired.