"I love these cookies but I really wanted to try to make them a little lighter. I actually used sweet potato puree for some of the butter and juice squeezed from an orange for some of the sugar and they still taste great. It sounds a little odd but try it!!"
Beat butter, sweet potato, white sugar, brown sugar, and orange juice with an electric mixer in a large bowl until smooth. Add eggs whites one at a time, allowing each egg to blend into butter mixture before adding the next. Beat in vanilla extract. Dissolve baking soda in hot water in a small bowl. Add to sweet potato batter. Stir in flour, chocolate chips, and walnuts. Roll dough into walnut-sized balls and place 2 inches apart onto ungreased baking sheets.
Bake in preheated oven until edges are nicely browned, about 10 minutes.