- 7 whole graham crackers, broken into rough pieces
- ½ cup all-purpose flour
- ¼ cup packed brown sugar
- ½ teaspoon table salt
- 8 tablespoons butter, cut into ½-inch pieces and chilled
- 6 (1.55-ounce) Hershey’s milk chocolate bars, divided
- 1 cup marshmallow creme
- 1 ½ cups mini marshmallows
- Adjust oven rack to middle position and heat oven to 425 degrees. Line an 8-inch baking pan with foil, leaving enough foil to hang over then edges. Generously spray foil with vegetable oil spray.
- Process graham cracker pieces in food processor until finely ground. Add flour, sugar, and salt and pulse to combine, about 6 to 7 pulses. Add butter and pulse until mixture resembles wet sand. Press dough into even layer in bottom of prepared pan. Bake until crust is set and well browned around edges, about 13 minutes. Let cool completely. (Cooled crust can be wrapped in plastic wrap and stored at room temperature for up to 2 days.)
- Cover crust completely with 5 chocolate bars, breaking bars as necessary to create fit (you will have some chocolate left over). Chop remaining chocolate fine and set aside. Spray offset spatula with cooking spray and use to spread marshmallow crème over chocolate. Sprinkle marshmallows evenly over marshmallow crème.
- Bake bars until edges are set and marshmallows are puffed and dark brown, about 15 minutes. Transfer pan to wire rack and sprinkle with chopped chocolate. Let bars cool until chocolate is set, at least 4 hours.
- Lightly spray chef’s knife with oil spray. Using foil overhang, lift bars out of pan. (Marshmallows may stick to foil. Use knife to separate, if necessary.) Cut bars into 16 squares. Serve. (Do not cut bars until ready to serve. Bars can be stored in airtight container at room temperature for up to 2 days.)