This chocolate sauce is thick, rich, and sweet. It’s the flavor combination that adults and children can agree on. If you prefer a more sophisticated taste that isn’t as sweet, cut the corn syrup by one tablespoon. Also, the espresso cuts the sweetness of the recipe but doesn’t give the sauce a coffee flavor. Refrigerate any leftovers (am I kidding?) in a plastic container with a tight-fitting lid for up to one week. The sauce will thicken as it chills. Heat the leftover sauce on low in a microwave oven or place the sauce in a heatproof bowl set over a pot or larger bowl that’s filled with hot water. Stir the sauce occasionally and let it set until it softens enough to pour.