Sweet Potato Casserole

1 (18 oz.) can sweet potatoes, drained
1 cup of granulated brown sugar substitute, divided
1/4 cup of skim milk
2 egg whites
1 tablespoon of margarine, melted
1 teaspoon of vanilla extract
Vegetable cooking spray
1 tablespoon of flour
1 tablespoon of margarine

Combine sweet potatoes, 3/4 cup brown sugar substitute, milk, egg whites, melted margarine, and vanilla, stirring until well blended. Spoon into a shallow baking dish coated with cooking spray.

Combine flour and remaining 1/4 cup brown sugar substitute; cut in 1 tablespoons margarine until mixture is crumbly. Sprinkle over potatoes, and bake at 350 degrees for 35 minutes or until thoroughly heated.