The leftover coffee is the perfect addition to chili!
Pour in more hot coffee.
Toss it and make fresh.
Microwaving would probably injure the delicate bouquet of an exquisite arabica. But when the cheap robustas are mostly what one can afford, the flavor is already so crude that microwaving don’t hurt it none. So I do that occasionally.
But what I like best and voted for was café au lait froid. I don’t get around to drinking much milk straight up. Like children will drink more milk if it’s chocolatized, I seem to have a similar but grownup preference for coffeeized milk. Goodness knows I need the calcium.
I think coffee on the heater for hours tastes worse than coffee microwaved the right amount, At work I drink heated coffee, but it goes fast enough to not be a problem, and the coffee is crap anyhow (but free.) At home we turn it off after we have the first, fresh cups, and microwave the rest.