1. Preheat your oven to 350°F (175°C) and line an 8×8-inch baking dish with parchment paper.
2. In a medium bowl, combine the melted butter and graham cracker crumbs until well mixed. Press this mixture evenly into the bottom of the prepared baking dish to form the crust.
3. In another bowl, mix the powdered sugar and peanut butter until smooth and creamy. Spread this peanut butter mixture over the graham cracker crust.
4. To make the chocolate topping, melt the chocolate chips and heavy cream together in a microwave-safe bowl, heating in 30-second intervals and stirring until smooth.
5. Pour the melted chocolate over the peanut butter layer, spreading it evenly with a spatula.
6. Refrigerate the bars for at least 2 hours, or until the chocolate is set. Cut into squares and serve chilled.

From my experience, patience is key here. Letting the bars set properly ensures that each layer holds its shape beautifully when cut. Trust me, the wait is worth it!