Desmond Hanan walks into the buffet area of John Jay Dining Hall—past the vegan, nut-free, and gluten-free stations, the crowds of people in front of the drink machines, the grill, and the salad bar. Then a Columbia College sophomore, Hanan navigates the dinner rush crowd to the desserts. Cakes sit on pedestals, soft serve swirls in its machines beside chocolate sprinkles and marshmallows, chocolate sauce, and warm caramel. This evening, they are also serving blondies—thick chocolate chip cookie squares—stacked into pyramids on a counter. He picks one up...