Final answer:
Mole sauce sometimes includes unsweetened chocolate, which contributes to its complex flavor profile and connects to its Mesoamerican origins where chocolate was a significant cultural element.
Step-by-step explanation:
The type of sauce that sometimes includes unsweetened chocolate is mole sauce. Mole is a traditional Mexican sauce with many variations, some of which include chocolate, which adds depth and richness to the flavor profile. Unsweetened chocolate has been a significant part of Mesoamerican culture, consumed originally in a drink combined with chili peppers, vanilla, and achiote by the Aztec. The bitter taste of raw cocoa beans is transformed into the chocolate flavor we recognize today through fermentation, roasting, and grinding. The use of chocolate in mole sauce is a homage to its cultural roots and historical use in the region, combining the rich, complex flavors of chocolate with other ingredients.