Preheat the oven to 180 °C (350°F) fan setting.
Mix together the melted butter and honey in a medium sized bowl until combined.
Add in the egg, vanilla essence and grated apples. Mix again.
In a small blender, whizz together the rolled oats until they’re like a coarse flour.
Add in the blended rolled oats and the oat bran to the mixture, along with the cinnamon and baking powder.
Take a 12 piece muffin tray and spray the base with an oil spray or line with muffin cases.
Spoon in the batter to each muffin case until level with the top.
Make the oat crumble by adding the ingredients into a small bowl. Spend a few minutes mashing them together with your fingers. You should end up with a coarse crumble.
Sprinkle this over the tops of your muffins.
Bake on the middle shelf of the oven for 12-15 minutes until golden. Give them a couple of minutes to cool down.