Start by melting the butter in a saucepan over low heat, gently stirring until it just begins to smell toasted and is smooth.
Add the graham cracker crumbs and brown sugar to the melted butter, stirring until the mixture resembles wet sand and is evenly coated.
Press this crumb mixture firmly into the bottom of your prepared baking pan, using the back of a spoon or your fingers to create a smooth, compact crust. Chill in the fridge for 15 minutes.
Meanwhile, in a mixing bowl, combine the creamy peanut butter, powdered sugar, and vanilla extract, mixing until smooth and creamy.
Spread the peanut butter mixture evenly over the chilled crust using a spatula, smoothing the top. Return to the fridge to set for 20 minutes.
In short bursts, melt the chocolate chips in the microwave, stirring between each interval until smooth and glossy.
Pour the melted chocolate over the peanut butter layer, spreading it evenly with a spatula. Gently tap the pan on the counter to settle the chocolate and remove any air bubbles.
Allow the bars to set at room temperature for about 30 minutes, then transfer to the fridge for at least 2 hours until firm and glossy.
Use a sharp knife to cut into squares, wiping the blade clean between each cut for neat, clean slices.
Serve the bars straight from the fridge or at room temperature for a softer bite. Enjoy this sticky, fudgy treat!
