I love a cup of coffee in the morning with a chocolate muffin. They just seem to go together. Coffee with chocolate gives me that extra boost of energy I need to get moving. I usually eat half of the muffin for breakfast and then finish the rest for a quick afternoon snack.
Mocha added to a recipe means coffee of some sort. If I have coffee leftover in a pot from our morning coffee, I just pour it in a jar and place it in the refrigerator. Then, I have it available for recipes I might make later that week. It will store in the refrigerator up to a week.
The coffee flavor should be subtle. It should enhance the flavor of the chocolate and not overpower added ingredients. Chocolate Mocha Muffins with Reese's Peanut Butter Chips is one example of using coffee with chocolate.