Corn syrup is an inverted sugar, a liquid version of table sugar. It can enhance Rice Krispies treats’ chewy texture and prevent the sugar from hardening into crystals.
They also help retain moisture to increase shelf life so your sweet treat doesn't dry out too quickly, as a Rice Krispies treat can’t be saved once dried out.
Incorporating this liquid is easy. Simply add a half cup of light corn syrup for every six cups of cereal while you melt your butter before adding the marshmallows.