You can Wake up in the Morning, put on a Pot of Coffee, and Have These Warm and Wonderful Muffins Ready in Under an Hour. Our recipe calls for a touch of instant espresso powder, which adds an unexpected and thoroughly delicious coffee flavor to the banana base. For those disinclined to early mornings, make these muffins the night before, as they keep really wonderfully (cool and wrap tightly in plastic wrap), and the banana flavor intensifies after a few hours.