Preheat oven to 375 degrees. Spray mini muffin tins with non-stick spray. Sift flour, baking soda and salt together and set aside. In the large mixing bowl of an electric mixer, cream the butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Mash the bananas with a fork. Add to the batter, mixing well. Slowly blend in the dry ingredients until well mixed. Fold in the chocolate chips. Fill muffin tins 3/4 full. Bake 15 - 20 minutes.