Preheat the oven to 190°C and line a muffin tray with muffin cases
Mash the bananas in a large bowl until they’re as smooth as you can get them. My 5‑year‑old loves this job - tiny hands, big enthusiasm. Once he’s done, I give the bowl a quick blitz with the electric whisk to chase away any last lumps. Add the maple syrup, egg, and 220g of the melted butter (save the remaining 50g for later). Whisk everything together until smooth.
Add the dry ingredients: flour, half of the cinnamon, baking powder, and salt. Mix in a bowl with the electric whisk, but gently - just until the dry ingredients disappear into the batter. No over‑whisking unless you enjoy tough muffins (you don’t) Fill the muffin cases about ¾ full) and bake for 20–23 minutes
Check for doneness by poking a muffin with a skewer - if it comes out clean, they’re ready.
Cool the muffins on a rack… or do what I do and tell my child they are too hot when he asks for one straight out of the oven and immediately eat one myself when he is not looking!
While they cool, mix the remaining cinnamon with the caster sugar in a shallow bowl.
Once the muffins are cool enough to handle, brush the tops with the remaining melted butter and dip each one into the cinnamon‑sugar mix until fully coated. This gives you that sweet, crunchy, ridiculously good cinnamon topping.
And finally - eat another one. You know… for quality control - Forking delicious!!