Sweet Potato-Coconut Cake

Cream butter and sugar until light and fluffy Add vanilla and mix well.
Sift together flour, baking powder, and salt Combine milk and buttermilk With mixer running, add flour and liquid to the butter mixture alternately in thirds, scraping down the sides of the bowl after each addition Add the 1/2 cup coconut and sweet potato and mix well.
Using a clean bowl and clean beaters or whisk, whip egg whites until stiff but not dry Fold into cake batter using over-under motion. Pour batter evenly into two greased 9-inch cake pans.
Bake in a preheated 350-degree oven for 25 minutes or until springy to the touch Turn cakes out onto cooling rack and allow to cool at room temperature.
Frosting.
Whisk sugar and water together, dissolving sugar completely Place on high heat and allow to come to rapid boil.
While water is boiling, whip egg whites on high speed When egg whites are stiff but not dry, add vanilla and sal. Remove boiling sugar water from heat and pour into egg whites in a slow, thin steam Continue whipping until mixture reaches room temperature This will take 8-10 minutes Add corn syrup and continue whiping on high speed until icing reaches spreading consistency.
When cake layers reach room temperature, frost and assemble cake. Sprinkle ouside of frosted cake with coconut, covering it completely.