Cooling is very important while you are cutting the brownies in a rectangular or square shape. But the vegan mug brownies can be served as cold or as hot as well immediately after removing the mug from the microwave. But again, there are no such rules; it is depending on your choice. No matter, it is hot or cold. All will go with your vegan mug brownie. You can serve with a cup of coffee or with a scoop of ice cream.