"This peanut butter pie is the real deal. No pudding or freezing. Any true Southerner knows a real peanut butter pie when they taste it and this is it. This recipe was passed on to me by a chef at a famous inn here in Virginia that served up some of the best pies in the state."
Stir confectioners' sugar and peanut butter together in a bowl until crumbly. Remove 2 tablespoons peanut butter mixture to a small bowl and reserve as a garnish. Spread remaining peanut butter mixture into the bottom of the pie crust.
Whisk milk, white sugar, flour, egg yolks, and salt together in a saucepan over medium heat until mixture begins to bubble and thicken, 5 to 10 minutes. Remove from heat and stir in butter and vanilla. Pour milk mixture over peanut butter mixture and cool pie completely in refrigerator, at least 2 hours.
Spread whipped topping over chilled pie and sprinkle reserved 2 tablespoons peanut butter mixture over the top.