Ingredients
Nonstick cooking spray
1 package (10 ounces) mini marshmallows
1/2 cup (1 stick) unsalted butter
1/2 cup smooth peanut butter
1/2 cup light corn syrup
1 box (10 ounces) puffed rice cereal (about 10 1/2 cups)
1 1/2 cups semisweet chocolate chunks or chips
Preparation
Coat a 9-by-13-inch baking dish with cooking spray. Line with wax or parchment paper, leaving an overhang on two sides; coat paper with cooking spray.
Combine marshmallows, butter, peanut butter, and corn syrup in a large (6-quart) pot; cook over medium heat, stirring, until melted and smooth, 5 to 8 minutes. Remove from heat. Add cereal; stir to coat.
Quickly transfer mixture to prepared dish, sprinkling in chocolate chunks as you go. Using a metal spatula coated with cooking spray, press in firmly. Refrigerate until chocolate is set, 10 to 15 minutes. Run a knife around edges; lift out of baking dish, using paper as an aid. Cut into bars.
