Bittersweet Chocolate takes a different approach. Fat and sugar are added to cocoa, without the milk to even out the bitterness. It tends to be harder, richer, and a common ingredient in baking, and is one of the foundational flavors in the richest chocolate drinks. The best way to celebrate Bittersweet Chocolate Day is to indulge your taste for the bitter side of things by picking up bittersweet chocolate.