I like to use the bananas when they have slighty darker skins as this brings out the natural sugars, adding the vanilla paste adds another flavour dimension to this tasty treat.
Preheat the oven to 200°C, gas mark 6. Line a 12 hole muffin tin with muffin cases.
Sift the flour into a large bowl and mix in the oats and sugar. In a separate bowl mash the banana and mix in the peanut butter, eggs, butter and milk at this stage you can add the vanilla paste. Stir all wet ingredients into the flour mixture.
Spoon into the muffin cases and bake for 15-20 minutes or until golden. Cool on a wire rack, if you can resist the temptation to eat them, once they have cooled sprinkle some some icing sugar.