In a separate large bowl blend the bananas, vanilla, both sugars, butter and egg. Stir the banana mixture into the flour mixture until it is moistened.
300 grams over ripe bananas, 1 teaspoon vanilla, 100 grams white sugar, 55 grams brown sugar, 75 grams butter, 1 medium egg
Spoon the mixture into the muffin tray. Bake for 10-12 minutes, till a metal skewer inserted in the centre comes out clean. Cool on a wire rack before adding the frosting.
Bring ingredients to room temperature - remove ingredients from the fridge around 30 minutes to bring to room temperature before you start on these muffins. If the butter is still quite chilled, it might help to chop it up into small cubes on a plate to bring it to room temperature quickly.Mixing the dry ingredients together first, ensures they are evenly distributed. Then, separately blend together the wet ingredients before combining with the dry. Stir together till the two mixtures are just combined. Be careful not to over-mix as this will result in dense and chewy muffins.Bake the muffins for around 12 minutes. Check them by inserting a clean knife through the centre of a muffin. If it comes out clean, they are ready, if it comes out sticky give them another couple of minutes.Cover and store in the fridge or in a cool part of the kitchen, consume within 3 days. Freeze the muffins in an airtight container for up to a month.