5 cups sweet potatoes, peeled and cubed
1 egg yolk
1/2 teaspoon cinnamon
2 tablespoon all-purpose flour
1 cup unsweet or natural applesauce
1 teaspoon vanilla extract
2 egg whites (room temperature)
1/2 cup brown sugar
1 tablespoon margarine (melted)

Preheat oven to 350 degrees.

Cook sweet potato in boiling water for 15 minutes until soft. Let cool. Put sweet potato and applesauce in a food processor (or blender). Blend until smooth. Add yolk, vanilla extract, and cinnamon. Mix until combined. Move to a large mixing bowl.

In a different bowl, beat egg whites until a stiff peak forms. Add one third of the whites into the sweet potato mixture. Fold the rest in gently. Don't let it disappear into the sweet potatoes.

Use a 1.5 quart casserole dish. Coat with cooking spray. Add the sweet potatoes to the dish.

In a separate dish combine the sugar, flour, and margarine. Sprinkle over the potatoes.

Bake uncovered at 350 degrees for 35 minutes.