Cake: Preheat oven to 350F. Grease two 9-inch cake pans and dust with flour. Place circles of wax paper in the bottoms of the pans and grease and flour them. Sift the flour, baking powder, and salt together. In a separate bowl, cream the sugar and butter, then add the eggs and vanilla and beat well. Add the dry ingredients and milk alternately, starting and ending with the dry ingredients, and beat until smooth. Pour the batter into the pans and bake 20-25 minutes. Cool on a rack, remove from the pans, and peel off the wax paper. Icing: Place the beaten egg whites in a saucepan, and add sugar, coconut and coconut milk. Over medium heat bring the mixture to a full boil, and boil 4-5 minutes. Remove from the heat, and spread on the cake while both the cake and icing are still warm. Makes a very moist coconut cake, serving 10-12.