Preheat oven to 350 ºF (175 ºC). Lightly grease a 9 x 5 inch loaf pan.
In a large bowl, combine flour, baking soda, salt and cinnamon.
In a separate bowl, cream together butter and brown sugar. Stir in eggs and mashed bananas until well blended.
Stir banana mixture into flour mixture just until moist (do not over-mix). Pour batter into prepared loaf pan.
Bake for 60 minutes, until a toothpick inserted into center of the loaf comes out clean. Let bread cool in pan for 10 minutes; turn out onto a wire rack.