Making the Bread Pudding
Preheat oven to 350 F. Grease all sides of a 2-quart baking dish with butter or nonstick cooking spray. Place French bread squares into greased baking dish. In a mixing bowl, beat sweet potatoes, evaporated milk, eggs, egg whites, molasses, cinnamon, nutmeg, and vanilla. Pour evenly over bread and press with hands to completely coat all sides of the bread in mixture. Bake 35 to 45 minutes or until pudding is just set. Allow to rest for 30-45 minutes.
Making the Praline Sauce
While the pudding is cooling, in a large heavy bottomed saucepan, add sugar, margarine, baking soda, and buttermilk on medium low heat, stirring frequently until sugar is dissolved. Mixture will foam, stir continuously to reducing foaming. Continue to cook until the color begins to caramelize. Cook until a light golden-brown color, approximately 20 to 30 minutes. Serve over sweet potato bread pudding.