In a food processor, blitz frozen peeled banana slices (it’s convenient to chop and freeze your own), crustless whole-grain bread, and cinnamon until finely chopped. Add yogurt and blitz again until smooth.
Serve your fro-yo right away, or you can hold it in a lovely scoopable state in the freezer for up to 40 minutes before it gets too hard. If you want to make it in advance, simply divide between ice-cube trays and freeze completely, then tip those into the food processor and whiz up again when you want to serve. Enjoy in a bowl, a cone, or a wafer, with a sprinkling of toasted nuts and seeds, and some extra fresh fruit to boost your intake.