Preheat oven to 350 degrees Fareneheit. Lightly grease a 9×5 inch loaf pan.
In a large bowl, combine 2 cups of flour, baking soda and salt. 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; stir just to moisten.
In a separate bowl, mix together the fresh blueberries with 1 tablespoon all-purpose flour. Then carefully fold into the muffin batter until well incorporated.
Spray cooking spray in muffin pans and then scoop batter into muffin cups. Repeat until all the batter is used.
Bake in preheated oven for 20 minutes, until a toothpick inserted into center of the muffin and it comes out clean. Let muffins cool in pan for 5 minutes, then carefully remove each muffin by using a spoon. Place on wire rack to cool completely.