Spray a 9x13-inch baking pan and a rubber spatula with nonstick cooking spray; set aside.
In a Dutch oven set over medium heat, add the corn syrup and sugar. Cook, stirring continuously, just until the mixture comes to a low boil and sugar dissolves.
1 cup light corn syrup, 1 cup granulated sugar
Remove from heat and add peanut butter and salt; stir until incorporated.
1 cup creamy peanut butter, ¼ teaspoon coarse sea salt
Add cereal and, using the sprayed spatula, stir until well coated.
6 cups Rice Krispies cereal
Spread and press the cereal mixture evenly into the prepared pan; set aside.
In a microwave-safe dish, melt the chips at 50% power, in 15-second intervals (stirring after every 15-seconds) just until the milk chocolate chips have melted. Remove the chips from the microwave and stir well. Let sit for 1 minute and stir again. Most (if not all) the chips should be melted (SEE NOTE).
1 cup milk chocolate chips, ½ cup butterscotch baking chips, ½ cup peanut butter baking chips
Spread the melted chips over the cereal mixture and set aside to harden – about 1 hour.