Chocolate slushies with toasted marshmallow and an ice cream s’more with chocolate sauce and graham cracker pieces at Coco S’more in Sunnyvale. Photo by Adrienne Mitchel.

The Toasted Marshmallow Shake and the S’mores Cookie are only available for a limited time while supplies last. Potbelly aims to keep the joy of summer going on National S’mores Day by treating Perks ...