Line 15x10x1-inch baking pan with heavy foil, extending foil over the edges of the pan; set aside.
In a large saucepan combine granulated sugar and corn syrup; heat and stir over medium heat just until mixture boils around edges. Heat and stir for 1 minute more. Remove from heat. Stir in peanut butter until smooth. Stir in rice cereal and cornflakes until coated. Press mixture into the bottom of the prepared pan. Place a piece of waxed paper over the mixture and press firmly with your hands; set aside.
For pudding layer, in a medium saucepan melt the 3/4 cup butter over medium heat. Stir in powdered sugar, pudding mixes, 1/2 cup of the chopped candy, and the milk. Spread pudding mixture over cereal layer; set aside.
For frosting, in a small saucepan heat and stir chocolate pieces and the 1/2 cup butter over low heat until melted and smooth. Spread frosting over pudding layer. Sprinkle with the remaining 1/4 cup chopped candy. Chill, uncovered, about 1 hour or until set. Cover for longer storage. To serve, use foil to lift uncut bars out of pan. Place on a cutting board; cut into bars.
From the Test Kitchen
TO MAKE AHEAD:
Layer bars between sheets of waxed paper in an airtight container; cover. Store in the refrigerator for up to 3 days or freeze for up to 3 months. Before serving, let stand at room temperature for 30 minutes.
Nutrition Facts (No-Bake Butterscotch Bars )
190 kcal cal.,
10 g fat
(4 g sat. fat,
1 g polyunsaturated fat,
3 g monounsatured fat),
10 mg chol.,
26 g carb.,
1 g fiber,
22 g sugar,
3 g pro.
Percent Daily Values are based on a 2,000 calorie diet