In a large bowl, mix the flour, powdered buttermilk, baking powder, and baking soda. In a separate bowl, whip the cream using an electric mixer; stir in milk, egg yolks, and melted butter. Stir the milk mixture into the dry ingredients until smooth. In a clean glass or metal bowl, whip egg whites to stiff peaks. Fold the egg whites and chocolate chips into the batter using a rubber spatula or wooden spoon. Preheat a waffle iron, and coat with cooking spray. Spoon batter onto the hot iron, and cook until there is no longer steam coming out and the waffles are light brown.