1. Preheat the oven to 325
2. Sift together the cake flour, baking soda,baking powder and salt.
3. Cream together the butter and sugar until light and fluffy. Best in the vanilla.
4. Add dry ingredients, alternately with the butter milk.
5. Using a clean bowl, beat 6 egg whites until stiff. Fold some of the stiff egg whites to the
Batter, then gently fold in the remaining egg whites.
6. Line 3 buttered 9 inch cake pans with wax paper.
7. Distribute batter evenly between the pans.
8. Bake in the pre-heated oven for 40 to 45 minutes or until the cake test done.
While the cakes are cooling prepare and chill the filling.
For the filling:
In the top of a double boiler, set over boiling water, melt butter. Whisk in the sugar, beaten eggs, juice and zest. Cook over the boiling water, stirring with whisk constantly, about 12 minutes or until well - thickened. Remove from the heat, add the flavoring, and chill, covered, before using.
For the frosting:
Combine water, sugar, vinegar , and salt in a heavy sauce pan. Cook over medium heat, stirring constantly, until clear. Without stirring cook until mixture forms a slender thread, or 242 degrees. Beat 3 eggs whites until stiff. Beating constantly add hot syrup. Continue beating until the frosting holds its shape.
Assembling the Cake:
Carefully cut each layer in half horizontally, to make 6 layers. Place filling between each layer. Add another layer of the cake, then filling, and so on. Topping with the last layer. Frost generously to cover top and sides. Then add the coconut. Refrigerate until served.