Aunt Patty swore this was her 4 ingredient secret weapon for potlucks

Lightly grease an 8×8-inch (or similar) ceramic baking dish, or line it with parchment paper, leaving some overhang for easy lifting later. Set the dish on your counter so it’s ready to go.
In a medium mixing bowl, stir together the graham cracker crumbs and peanut butter. Pour in the melted butter and mix until everything is evenly combined and the mixture looks like thick, slightly crumbly dough that holds together when pressed.
Transfer the peanut butter–graham mixture to the prepared baking dish. Use the back of a spoon or clean hands to firmly press it into an even, compact layer, making sure to reach all the corners. This will be your thick tan, crumbly base.
Place the chocolate chips in a microwave-safe bowl. Microwave in 20–30 second bursts, stirring well after each, until the chocolate is completely smooth and melted. (Alternatively, melt them gently in a heatproof bowl set over a pot of barely simmering water, stirring until glossy.)
Pour the melted chocolate over the pressed base in the baking dish. Tilt the dish and use an offset spatula or the back of a spoon to spread the chocolate into a smooth, even layer that fully covers the peanut butter base.
Let the bars cool at room temperature for about 20–30 minutes, then transfer the dish to the refrigerator. Chill for at least 1–2 hours, or until the chocolate is firm and the base has set.
Once fully chilled, remove the dish from the fridge. If you used parchment, lift the whole slab out onto a cutting board. Use a sharp knife to cut into 16 squares (or smaller bite-size pieces for a big potluck crowd).
Serve the bars straight from the ceramic baking dish or arranged on a platter. Store any leftovers covered in the fridge for up to 5 days. For cleaner slices at parties, keep the dish chilled until just before serving—this is exactly how Aunt Patty kept her tray looking perfect, at least until it vanished.
Variations & Tips