This is a Southern classic.

1 1/2 cups vegetable oil
2 cups granulated sugar
4 eggs, separated
1 1/2 cups finely shredded uncooked
    sweet potato (about 1 medium)
1/4 cup hot water
1 teaspoon vanilla extract
2 1/2 cups cake flour
3 teaspoons baking powder
1 teaspoon ground cinnamon
1 teaspoon ground nutmeg
1/4 teaspoon salt
1 cup chopped pecans

In a mixing bowl, beat oil and sugar. Add egg yolks, one at a time, beating well after each addition. Add sweet potato, water and vanilla extract; mix well.

In a small mixing bowl, beat egg whites until stiff; fold into the sweet potato mixture.

Combine flour, baking powder, cinnamon, nutmeg and salt; add to potato mixture. Stir in pecans. Pour into three greased 9-inch round cake pans. Bake at 350 degrees F for 22 to 27 minutes or until a wooden pick inserted near the center comes out clean. Cool for 10 minutes before removing to wire racks.

Frosting
1/2 cup butter
1 1/3 cups granulated sugar
2 (5 ounce) cans evaporated milk
4 egg yolks, beaten
2 2/3 cups flaked coconut
1 cup chopped pecans
2 teaspoons vanilla extract

Melt the butter in a saucepan; whisk in sugar, milk and egg yolks until smooth. Cook and stir over medium heat for 10 to 12 minutes or until thickened and bubbly. Remove from the heat; stir in the coconut, pecans and vanilla extract. Cool slightly. Place one cake layer on a serving plate; spread with a third of the frosting. Repeat layers.