Line a 9x9-inch baking pan with parchment paper or foil, then set aside.
In a large microwave-safe bowl, melt the butter in the microwave. Add graham crackers, powdered sugar, 1 cup + 2 tablespoons of peanut butter, vanilla, and salt. Mix until combined.
Press the mixture into the bottom of the prepared pan, creating an even layer.
In a small microwave-safe bowl, add the chocolate chips and the remaining 2 tablespoons of peanut butter. Microwave to melt, then stir until smooth. Spread over the top of the pressed mixture.
Place the pan in the refrigerator to chill for at least 2 hours. The bars should be firm.
To cut, remove from the refrigerator and slice with a sharp chef's knife. Serve cold or at room temperature.
Notes
To STORE No-Bake Peanut Butter Bars, place them in an airtight container and refrigerate for about a week. You can eat them straight from the fridge or let them come to room temperature before serving.To FREEZE these, you can either wrap individual bars or the whole slab in plastic wrap, then wrap it a second time in foil and place it in a freezer-safe bag. Freeze for up to 3 months. Let them defrost and come to room temperature before serving.