Prepare a space that you can use to dip out mounds of your cereal mixture. You can use parchment covered cookie sheets, bread boards or your counter.
Measure 12 cups of Chex cereal into a large bowl that has been sprayed with non-stick spray or very lightly buttered.
In a medium sauce pan over medium heat, stir together the corn syrup and granulated sugar. Stir this mixture occasionally until the sugar has melted and the mixture comes to a rolling boil. As soon as it comes to a boil, remove it from the heat and carefully add 3 cups of peanut butter. Stir well until the peanut butter is all melted and the mixture is smooth.
Pour the peanut butter mixture over the cereal in your prepared bowl. Gently fold the cereal and ooey gooey peanut butter mixture together until the cereal is covered.
Use an ice cream scoop or large spoon to drop mounds of the coated cereal onto your prepared surface, flattening the tops slightly. Let the mounds set up a little while you prepare the topping.
To a microwave safe bowl, add 3 cups of butterscotch baking chips. Microwave these on 50% power for several minutes until very nearly melted, stirring every 30 seconds to 1 minute. When they are almost melted, add 3 cups of semi-sweet chips and ½ cup of creamy peanut butter. Continue to microwave on 50% power, stirring every 30 seconds or so until everything is melted and smooth.
Once melted, use a large spoon to cover just the tops of the cereal mounds with large dollops of the chocolate mixture. Allow the chicken butts to set up completely before removing them to storage containers.