For the crispy crust layer: Put the cereal in a large bowl and set aside. Lightly spray a paper towel with nonstick cooking spray and use it to rub the bottom and sides of an 8-inch-square baking pan.
Into a small saucepan, pour 1/4 cup water. Gently add the sugar and corn syrup (do not let any sugar or syrup get on the sides of the pan) and use a small wooden spoon to stir the mixture until just combined. Put a candy thermometer in the saucepan. Cook over medium-high heat and bring to a boil. Cook until the mixture reaches the soft-ball stage, 235 degrees F. Remove from the heat, stir in the butter and pour the mixture over the cereal. Working quickly, stir until the cereal is thoroughly coated, and then pour it into the prepared pan. Using your hands, press the mixture into the bottom of the pan (do not press up the sides). Let the crust cool to room temperature while you make the next layer.
For the milk chocolate peanut butter layer: In a large nonreactive metal bowl, stir together the chocolate and the peanut butter. Set the bowl over a saucepan of simmering water and cook, stirring with a rubber spatula, until the mixture is smooth. Remove the bowl from the pan and stir for about 30 seconds to cool slightly. Pour the mixture over the cooled crispy crust layer. Put the pan in the refrigerator until the top layer hardens, about an hour.
For the chocolate icing: In a large nonreactive metal bowl, combine the chocolate, corn syrup and butter. Set the bowl over a saucepan of simmering water and cook, stirring with a rubber spatula, until the mixture is completely smooth. Remove the bowl from the pan and stir for 30 seconds to cool slightly. Pour the mixture over the chilled milk chocolate peanut butter layer and spread into an even layer. Put the pan in the refrigerator until the topping hardens, about an hour.
Cut into 9 squares and serve. The bars can be stored in the refrigerator, covered tightly, for up to 4 days.
This recipe was provided by a chef, restaurant or culinary professional and may have been scaled down from a bulk recipe. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.