Preheat your oven to 350 degrees Fahrenheit and line your muffin tin with 12 paper muffin cups.

In a large mixing bowl, mash the bananas with a fork until no large pieces remain.

Add the sugar, egg and oil and mix with a wooden spoon until everything is incorporated.

Measure the flour, baking powder, baking soda and salt on top of the wet ingredients and stir them gently with a fork.

Using a wooden spoon, carefully mix the wet and the dry ingredients together.

Spoon the batter into 12 lined muffin cups, filling them evenly.

Bake the muffins in the oven at 350 degrees for about 23 minutes, or until golden brown.

Let them cool in the tins for about 5 minutes and then turn them out to cool completely on a cooling rack.