Peel and slice the bananas, then freeze for at least 6 hours or overnight until completely solid.
Put the frozen banana slices, frozen mixed berries, milk and vanilla extract into a blender or food processor.
Start blending on a low setting, then gradually increase the speed. Stop occasionally to scrape down the sides until the mixture is smooth and creamy – this should take about 3–5 minutes. If it’s too thick, add a little more milk, one teaspoon at a time.
If you like, blend in the maple syrup or honey until it’s evenly combined.
Spoon the ice cream into bowls and serve straight away for a soft-serve consistency.
To store any leftovers, transfer to an airtight container and freeze for up to a week. When you’re ready to serve, leave it at room temperature for 10–15 minutes to soften, or blitz it briefly in the blender.