Line the bottom circle of a 9-inch fluted tart pan with parchment paper and lightly spray with non-stick spray, set aside.

In a medium microwave safe bowl, add the chocolate and vegetable oil and melt on 30 second increments in the microwave, stirring in between, until melted and smooth.

Spoon half of the melted chocolate into the prepared pan and evenly spread over the bottom and the sides of the pan. Be sure to get into the little grooves on the side. Chill while you prepare the filling.

In a medium bowl, whisk together the powdered sugar and graham cracker crumbs, set aside.

In another medium microwave safe bowl, add the peanut butter and butter and melt on 30 second increments in the microwave until melted and smooth.

Pour the peanut butter mixture over the graham and sugar mixture and stir until completely incorporated.

Remove the tart pan from the refrigerator. Spread the peanut butter mixture evenly on top of the melted chocolate layer and smooth.

Spoon the remaining melted chocolate on top of the peanut butter filling and smooth all the way to the sides.

Chill in the refrigerator for at least 4 hours to overnight.

When you are ready to serve, gently press up on the circle on the bottom of the tart pan and gently wiggle. The peanut butter cup should release. Remove the metal circle and the parchment from underneath. Feel free to use a hot butter knife to fix any imperfections along the sides of the peanut butter cup. Place on a serving tray, cut, and enjoy!