First freeze your bananas either overnight or for at least 2-3 hours. Make sure to peel them before freezing and either put them in a freeze safe bag or on a pan lined with parchment paper.
Once bananas are frozen, add them to a high speed blender or food processor. Blend until smooth and creamy. I like using the food processor best. You might have to stop and scrape it down a few times.
Put the ice cream in a freezer safe container and freeze for at least an hour.
When you're ready to serve, first prepare the espesso, coffee or tea.
Scoop the ice cream into a glass, pour espresso over it and enjoy immediately!