Easy Banana Bread

5 ripe bananas
1 (18 1/2 oz.) box Duncan Hines yellow cake mix
3 eggs
1 tsp. vanilla
1/2 cup chopped nuts, optional

Preheat oven to 350 degrees. In large bowl mash bananas and add remaining ingredients. With electric beater, mix two minutes at medium speed. Pour into buttered 5 x 9 inch loaf pan and bake one hour.