01 -
Line a 9x13-inch pan with parchment paper, leaving overhang on two sides for lifting out the bars later.
02 -
In a large bowl, stir together the melted butter, creamy peanut butter, vanilla, and fine salt until smooth.
03 -
Add the graham cracker crumbs and powdered sugar. Stir until fully combined and thick, with no dry streaks at the bottom of the bowl.
04 -
Transfer the mixture to the prepared pan. Press firmly into an even layer using a spatula or the bottom of a measuring cup. Chill while you make the topping.
05 -
Combine the chocolate chips and coconut oil in a microwave-safe bowl. Microwave in 20-second bursts, stirring after each, until smooth and melted.
06 -
Pour the melted chocolate over the peanut butter base and spread evenly. Add flaky salt if using. Refrigerate for at least 2 hours, until firm.
07 -
Lift the chilled slab from the pan. Cut into 24 squares with a sharp warm knife, wiping the blade between cuts for clean edges.