Preheat the oven to 350 degrees and line a 12-count muffin tin with muffin liners and grease lightly.
In a large mixing bowl, add the bananas and mash them well. Add the eggs and whisk until smooth. Stir through the brown sugar., then fold in the flour until just combined. If adding any mix-ins, fold them through at the end.
Evenly distribute the batter amongst the muffin tin, filling them 2/3 of the way. Bake the muffins for 18-20 minutes or until a toothpick comes out clean.
Let the muffins cool in the tin for 5 minutes before carefully transferring them to a wire rack to cool completely.
Notes
TO STORE. Store banana muffins in an airtight container at room temperature for 3 to 4 days. TO FREEZE. For the best results, freeze the muffins individually wrapped with food wrap. Defrost the muffins at room temperature and use the oven to reheat them if needed.