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 into a separate mixing bowl and stir them together with a fork. Once they’re mixed together, dump the dry ingredients into the wet ingredients.
Using a wooden spoon, carefully mix the wet and the dry ingredients together. The danger here is over-mixing which will result in dense, flat and dry muffins. The best technique for mixing is to scoop underneath the mixture and pull up gently instead of stirring around in a circle (like you’d stir your coffee, for example). Continue mixing this way just until the dry ingredients have been incorporated. It’s fine if there are a few small streaks of flour in the batter; it’s the large pockets of flour you want to make sure are incorporated.
Spoon the batter into 12 lined muffin cups. Try your best to ensure you fill the cups evenly. This will ensure each of the muffins is finished baking at the same time (you don’t want some over-baked and some raw in the middle!)
Bake the muffins in the oven at 350 degrees for about 23 minutes (anywhere from 22-25 minutes, depending on your oven), or until they are golden brown.
Let them cool in the tins for about 5 minutes and then turn them out of the tins to let them cool completely on a cooling rack. Or, enjoy one warm from the oven slathered in butter.
These muffins can be stored in an airtight container for up to 4 days, although they’ve never lasted that long in our house!