Preheat the oven to gas mark 4/350oF/180oC/160oC fan and line a 12-count muffin tin with muffin cases.
Gather two mixing bowls and to one of the bowls add the flour, bicarbonate soda, salt, cinnamon and nutmeg then whisk them together and set aside.
To the second bowl, add the oil, sugar, vanilla extract, eggs and yoghurt all at one time then mix them together using a wire whisk.
Pour the dry ingredients into the bowl with the wet ingredients and combine well. Add and mix in the mashed banana and grated carrots.
Spoon the batter equally between the 12 muffin cases and bake in the oven for 23 – 25 minutes.
Once baked, place the muffin tin on a cooling rack for 15 minutes then remove the muffins from the tin and place them directly onto the cooling rack to completely cool.