Prep your pan. Line an 8x8-inch (20x20 cm) square pan with parchment paper, leaving overhang on two sides for easy lifting. Lightly grease the parchment for clean slices.

Combine the dry base. In a large bowl, stir together graham cracker crumbs and powdered sugar until evenly mixed and lump-free.

Mix the peanut butter base. Add melted butter, 1 cup peanut butter, vanilla, and salt. Stir until the mixture is smooth and thick, like a soft dough. It should hold together when pressed.

Press and level. Transfer the peanut butter mixture to the prepared pan. Press it firmly into an even layer using a spatula or the bottom of a measuring cup. Pack it tight for a clean bite.

Melt the chocolate. In a microwave-safe bowl, combine chocolate chips and oil. Microwave in 20–30 second bursts, stirring after each, until smooth and glossy. Alternatively, melt over a double boiler.

Optional swirl. For a peanut butter swirl, stir 2 tablespoons of peanut butter into the melted chocolate in streaks. Don’t fully mix—just swirl lightly.

Top the base. Pour the melted chocolate over the peanut butter layer. Tilt the pan or use an offset spatula to spread it evenly. Tap the pan gently to release air bubbles.

Chill to set. Refrigerate for at least 2 hours, or until the chocolate is firm and the base is set.

Slice smart. Lift the block out using the parchment. For clean edges, warm a sharp knife under hot water, dry it, and cut into squares or bars. Wipe the blade between cuts.

Serve or store. Enjoy immediately or pack into an airtight container. Keep chilled for best texture.