Try this Puppy Chow #1 recipe, or contribute your own.
Swapping the margarine for an equal weight of salted butter alters the moisture content and structural integrity of the fat phase, producing a crisper shell once cooled. Without careful temperature control during the melting phase, the high sugar content in chocolate and butterscotch chips will easily scorch or seize into a grainy mass when exposed to direct heat.
Stored in an airtight container at room temperature, these pieces actually improve by the second day as the residual fats fully migrate into the cereal matrix and soften any brittle edges. Humidity is the primary enemy during storage, causing the powdered sugar to dissolve into a sticky glaze if the container is left unsealed.