Preheat oven to 350 degrees. In a bowl mix graham cracker crumbs and melted butter. Bake for about 5 to 10 minutes. Remove from oven and allow to cool to room temperature.
In a large bowl cream heavy cream until it forms stiff peaks. With a stand mixer, or another clean bowl cream together cream cheese, peanut butter, brown sugar, vanilla and beat until the mixture is smooth and creamy. Gently fold the whipped cream into the peanut butter mixture. Spoon the peanut butter mixture into the pie shell or tart pan. Place the pan into the refrigerator.
Chill for about 1 hour or until the pie sets. In a small saucepan heat, the 1/2 cup heavy cream until it just begins to boil. Add the chopped chocolate to the pan. Stir until the chocolate melts completely. Spread the melted chocolate over the peanut butter pie. Chill pie until the chocolate sets. This pie must be kept in the refrigerator.