Preheat oven to 180°ase a 6-hole jumbo muffin pan.
In a bowl, mix together yogurt, honey, oil, egg and vanilla. Whisk in banana. Sift flour, bicarbonate of soda and cinnamon over wet mixture. Fold together lightly, taking care not to over-mix. Batter should still be a little lumpy.
Fill prepared pans. Sprinkle with a little extra cinnamon, if desired. Bake for 25-30 minutes, until cooked when tested.
If desired, slice another banana and arrange on baking paper on a heatproof plate. Microwave on high for 5 minutes to dry, then use to top muffins before baking.