Spray a 9-inch baking dish with nonstick cooking spray.
Heat the sweetened condensed milk and unsweetened chocolate in a medium saucepan over medium-low heat until chocolate is melted and mixture thickens, about 10 minutes.
Remove the pan from the heat, and stir in the graham cracker crumbs and half of the chopped peanut
Spread in the prepared pan. Top with the remaining peanut.