Preheat oven to 325°. Spray a non-stick loaf pan with cooking spray.
Mash bananas in a bowl, set aside. In a medium bowl, combine flour, baking soda and salt with a wire whisk. Set aside.
In a large bowl cream butter and sugar with an electric mixer. Add egg whites, bananas, apple sauce, vanilla; beat at medium speed until thick. Scrape down sides of the bowl.
Add flour mixture, then blend at low speed until combined. Fold in chocolate chips. Do not over mix.
Pour batter into muffin pan; bake on the center rack for about 40 minutes, or until a toothpick inserted in the center comes out clean.