- Preheat the oven to 375°F. Grease a standard muffin tin, or line with papers and grease the papers.
- Combine the yogurt, egg, oil, mashed banana, sugar, and oat bran in a bowl. Whisk together and set aside for 10 minutes.
- Whisk together the flour, baking powder, salt, baking soda, and nutmeg.
- Work the topping ingredients together until the mixture is crumbly.
- Whisk the banana mixture into the flour mixture. Scoop into the prepared muffin cups, filling them almost full; the muffins won't rise much.
- Sprinkle muffins with the topping.
- Bake the muffins for 20 to 24 minutes, until the muffins are set and browned. Remove from the oven and let rest in the pan for 5 minutes. Remove from the pan and enjoy warm.