Preheat oven to 300 degrees F (150 degrees C). Grease 2 - 9x5 inch loaf pans. In a medium bowl, mash bananas and stir in the eggs until well blended. Set aside.
In large bowl, beat shortening and gradually add sugar. Stir in vanilla and banana mixture. Whisk together flour, baking soda, and salt; blend into batter. Add walnuts if desired. Divide between the prepared pans.
Bake for 1 hour 15 minutes in the preheated oven, or until a toothpick inserted into the center of the loaf comes out clean.