Preheat oven to 350 degrees. Line muffin pan with liners (or coat with nonstick cooking spray.)
Combine flour, baking soda, cinnamon and salt in a large mixing bowl. In a separate bowl, use a mixer to cream together butter and brown sugar. Fold in the eggs, chocolate chips and mashed bananas until well blended.
Add the banana mixture to the flour mixture and stir until moistened.
Fill each muffin cup about 3/4 full with batter. Bake for 18-22 minutes, or until done in the middle (test with a toothpick). Muffin tops will begin to brown. Allow to cool in the pan for 10 minutes, then remove to cooling rack or countertop.