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

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

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

In a large bowl, whisk together powdered sugar and graham cracker crumbs.

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

Add the peanut butter mixture to the powdered sugar and crumb mixture. Stir until well combined.

Pour the peanut butter filling into the prepared tart pan, smoothing it into an even layer.

Spread the remaining melted chocolate over the peanut butter layer. Use a spatula to smooth the top.

Refrigerate for at least 4 hours or until the chocolate is set.

Once cooled, gently remove the pie from the tart pan, peel off the parchment, and serve.