Line the pan: Use parchment paper with overhang on two sides. This makes lifting the bars out clean and easy.

Make the base: In a large bowl, stir together melted butter, 1 1/4 cups peanut butter, powdered sugar, graham cracker crumbs, vanilla, and salt. Mix until it looks like thick, uniform cookie dough. It should hold together when pressed.

Press it in: Transfer the mixture to the lined pan. Use the back of a spoon or a flat-bottomed glass to press it firmly into an even layer. Pack it tightly so the bars slice neatly later.

Melt the topping: In a microwave-safe bowl, combine chocolate chips, 1/2 cup peanut butter, and oil. Microwave in 20–30 second bursts, stirring between each until smooth. Or melt gently on the stove using low heat.

Top the base: Pour the warm chocolate mixture over the peanut butter base. Tilt the pan or use a spatula to spread it into an even, glossy layer.

Chill: Refrigerate for 2–3 hours, or until the chocolate is set and the base feels firm. For ultra-clean cuts, chill at least 4 hours or overnight.

Slice: Lift the slab out using the parchment. Let it sit at room temperature for 5–10 minutes before cutting to prevent the chocolate from cracking. Use a sharp knife warmed under hot water and wiped dry for smooth edges. Add flaky sea salt before the chocolate fully sets if using.

Serve: Cut into 16 modest squares or 9 large ones. They’re rich, so smaller bites go a long way.