Sweet Potato Muffins

I need to give credit, so here's where this recipe came from.

Ingredients:
3 cups flour
1-1/2 teaspoon baking powder
1 1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup sugar
1-1/2 tsp. ground cinnamon
2 cups sweet potatoes, cooked and mashed
2 whole eggs
3 egg whites
1 teaspoon vanilla extract
1 cup low-fat buttermilk
1 cup applesauce
1/2 cup raisins
1/4 cup chopped nuts (optional)               
1/4 cup brown sugar, packed

Directions:
Preheat oven to 350 degrees. Line 24 muffin tins with paper liners, or coat with nonstick spray. In a large bowl, combine the flour, baking powder, baking soda, salt, sugar and cinnamon. Mix well. In another bowl, combine the sweet potatoes, eggs, egg whites, vanilla, buttermilk and applesauce. Mix well. Make a well in the center of the dry ingredients and pour the wet ingredients in. Add the raisins and nuts, and combine with as few strokes as possible, until all ingredients are just moistened.
Fill the 24 prepared muffin cups with batter. Add 1/2 teaspoon brown sugar to the top of each muffin. Bake at 350 degrees for 22-25 minutes, or until a toothpick comes out clean. Cool for 5 minutes before removing from pans to wire racks. Makes 24 muffins.