Peel the bananas and place on a large sheet of foil, sprinkle with the brown sugar, rum, cinnamon and vanilla essence

Draw up the foil to make a package and bake in an oven at 160c for 15 minutes

Remove from the oven and allow to cool

Mix together all the remaining dry ingredients in a large bowl.

Melt the butter (I do this in the microwave on short bursts of 20 seconds) and allow to cool. Preheat the oven to 180c

Mix together the egg, milk and butter and whisk well

Mash up the banana and liquid and then stir into the egg mixture

Make a well in the centre of the dry ingredients and gradually add in the liquids

Mix gently with a fork so you have a kind of gooey paste. I found that it was important to pull in the mixture from the bottom of the bowl carefully, but you also need to be gentle and not overmix. A lumpy paste is what you want! Stir through the chocolate chips if you are using them

Spoon into pre greased or lined muffin tins and bake for 20 minutes at 180c

Allow the muffins to cool for 5 minutes before you turn them out