To make the cake: Combine first three ingredients and set aside. Combine milk, water and vanilla, set aside. Beat egg whites (at room temperature) until foamy. Gradually add 1/4 cup sugar, 1 tablespoon at a time, beating until soft peaks form. Set beaten egg whites aside. Combine shortening, butter and sugar in a large mixing bowl; beat at medium speed with electric mixer for 3 minutes. Add flour mixture alternately with milk mixture, beginning and ending with flour mixture. Mix after each addition. Fold in beaten egg whites. Pour batter into 3 greased and floured 9-inch cake pans. Bake at 350 degrees for 15 to 20 minutes or until it tests done. Cool in pans on wire rack 10 minutes; remove from pans and let cool completely. Spread Lemon-Apricot Filling between layers and Fluffy White Frosting on sides and top of cake. Sprinkle with coconut on sides and top of cake. Garnish if desired.
Lemon-Apricot Filling: Combine first seven ingredients in a medium saucepan. Stir well. Bring to a boil over medium heat, stirring constantly; boil 3 to 4 minutes or until thickened. Reduce heat, and cook 1 minute, stirring constantly. Gradually stir about one-fourth of hot mixture into egg yolks; add to remaining hot mixture. Remove from heat; stir in lemon rind; cover and chill 1 hour. Yield: 2 1/2 cups
Fluffy White Frosting: Combine all ingredients except vanilla in top of double boiler. Beat at low speed with electric mixer 30 seconds or just until blended. Place over boiling water; beat constantly at high speed 7 minutes or until stiff peaks form. Remove from heat. Add vanilla; beat 2 minutes or until thick enough to spread. Yield: 4 1/4 cups