1Preheat oven to 350 degrees.
Grease & flour 3- 8", or 3-9" cake pans, & set aside
Combine oil, sugar, 4 egg yolks & hot water, just until combined.
3In another bowl combine dry ingredients, and add to oil mixture. Mix just until moistened. Stir in sweet potatoes, nuts & vanilla.
4In another bowl, beat 4 egg whites until stiff, but not dry. Fold in batter, & try not to deflate the egg whites.
5Pour into prepared cake pans. cool cakes on wire rack, & frost middle & top of cake only.
6Creamy Coconut Frosting:
Combine all ingredients for frosting, except coconut, in a deep pot, or ( dutch oven). Cook on medium heat, about 12 minutes, stirring constantly, until thick. Remove from heat, & stir in coconut, and cool. Frost middle & top of cake.