I would not hesitate to substitute sweet potatoes for the pumpkin in this recipe. I don't have a trouble with cream cheese frosting being light and fluffy. I think it has to do with the proportion of butter, cream cheese and butter.

Pumpkin cake
1 cup brown sugar
1 cup white sugar
1 cup vegetable oil
4 eggs
2 cups all-purpose flour
2 teaspoons baking soda
1 teaspoon baking powder
1 1/2 teaspoons ground cinnamon
1/2 teaspoon ground nutmeg
1/2 teaspoon ground ginger
2 teaspoons pure vanilla extract
1/2 teaspoon salt
2 cups pumpkin puree or cooked mashed pumpkin
cream cheese frosting, below
1/2 cup chopped pecans

Directions for pumpkin cake
Mix sugar, vegetable oil, and eggs in a large mixing bowl; mix well.
Sift dry ingredients into a separate bowl
stir into oil mixture, beating well. Stir in pumpkin puree.
Pour batter into two greased and floured 9-inch round layer cake pans. Bake at 350° for 35 to 40 minutes. Turn out onto racks to cool. Frost pumpkin cake with cream cheese frosting and top with chopped pecans.

Cream cheese frosting
1 stick butter
8 oz cream cheese
1 pound powdered sugar
1 teaspoons pure vanilla extract
Beat cream cheese and butter together, beat in sugar and beat until well blended....add vanilla.

Linda, thanks for the recipe, I am certainly going to try it this week substituting sweet potatoes for the pumpkin as the spices sound pretty close in my mind. Do you split the layers and frost?

Thanks again.

Brenda