In a mixing bowl, combine graham cracker crumbs and melted butter. Mix until the crumbs are evenly coated.
Press the graham cracker mixture into the bottom and up the sides of a 9-inch pie dish to form the crust. Chill in the refrigerator for 10 minutes.
In a separate bowl, beat together the peanut butter, powdered sugar, and vanilla extract until smooth and creamy.
In another bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the peanut butter mixture until fully combined.
Pour the peanut butter filling into the chilled crust and spread it evenly. Place back in the refrigerator while you prepare the chocolate topping.
In a small saucepan, combine the semi-sweet chocolate chips and vegetable oil. Heat over low heat, stirring until melted and smooth. Remove from heat and allow to cool slightly.
Pour the melted chocolate over the peanut butter layer, spreading it evenly with a spatula.
Refrigerate the pie for at least 2 hours or until set.
Slice and serve chilled.