Preheat oven to 350 degrees F. Lightly grease a muffin tin or line with paper liners. Set aside.
In a large mixing bowl combine the flour, sugar, baking soda and salt. Set aside.
In another large mixing bowl combine the mashed bananas, eggs, buttermilk, butter and vanilla. Add to the dry ingredients and mix just until combined. There should be small lumps in your batter. With a large cookie scoop or spoon fill each cup or liner 3/4 full. Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean.
Notes
These muffins can be stored in an airtight container or plastic ziptop bag for 3-4 days on the counter. These muffins can be frozen in an airtight container or freezer bag for up to 3 months. Let thaw overnight and reheat in the microwave if desired.