Preheat oven to 350 degrees F and line a cupcake pan with muffin/cupcake papers or spray with nonstick cooking spray OR lightly grease a 9x5 inch loaf pan.
In a large bowl, combine flour, baking soda, cinnamon and salt.
In a separate bowl, cream together butter and brown sugar, and vanilla. Stir in eggs and mashed bananas until well blended.
Add flour mixture slowly, about 1/2 cup at a time until combined.
Pour batter into prepared loaf pan or muffin pan filling each cup about 3/4 full.
Bake in preheated oven for 16-18 minutes for muffins, and about 60 minutes for a bread or until a toothpick inserted into center comes out clean.
Let cool in pan for 10 minutes, then place on a wire rack to finish cooling.