Line the bottom of a 9-inch tart pan with parchment paper and lightly spray with nonstick spray.

Combine chocolate chips and vegetable oil in a microwave-safe bowl and heat for 45-55 seconds. Stir until smooth and melted.

Spread half of the melted chocolate evenly over the bottom and sides of the tart pan. Chill while preparing the filling.

Whisk together powdered sugar and graham cracker crumbs in a bowl.

In a microwave-safe bowl, heat chunky peanut butter and butter for 45 seconds, then stir to combine.

Pour the peanut butter mixture over the powdered sugar and graham cracker crumbs and mix well.

Spread the peanut butter filling evenly over the chilled chocolate shell.

Top with the remaining melted chocolate, smoothing it out to cover the filling completely.

Refrigerate the pie for at least 4 hours or until set.

Gently remove from tart pan, peel off parchment, and slice into wedges to serve.