Lemon Coconut Cake

Preparation : Cake: Set oven for moderately hot, 375~F. Grease two round 8-inch cake pans. Sift together the flour, baking powder and salt. Whip egg whites until stiff but not dry. Cream shortening well; gradually beat in sugar. Beat until well blended. Stir in vanilla. Add sifted dry ingredients alternately with milk, a little at a time, stirring only until smooth after each addition. Gently fold in whipped egg whites. Turn batter into pans. Bake 25 to 30 minutes or, until cake springs back when lightly touched with fingertip. Cool cake slightly, 1o to 15 minutes, in pans on a rack. Emove from pans; cool. Filling: Mix together sugar, flour; gradually add warm water. Stir in 3 well-beaten egg yolks. Cook over hot water until thick; stirring constantly. Cover; cook 5 minutes longer. Remove from heat; add grated lemon peel, lemon juice and butter or margarine. Mix well, cool. Spread Lemon Filling between layers. Frosting: Combine sugar, water, and vinegar in a saucepan. Place over moderate heat; stir until sugar dissolves. Boil without stirring to 236~F on a candy thermometer or until syrup spin a thread when dropped from the tip of a spoon. Whip egg whites until stiff but not dry. Pour hot syrup slowly over egg whites, beating constantly with a rotary or electric beater. Continue beating until frosting holds its shape. Stir in vanilla. Frosts top and sides of one, 8-inch layer cake and sprinkle with coconut.