Heat oven to 350 degrees F. Grease two 9-inch-round layer-cake pans; dust with flour; tap out excess flour.
Sift together the cake flour, baking powder and salt onto sheet of waxed paper.
Combine milk, water and vanilla in small bowl.
Beat egg whites in clean bowl with clean beaters until frothy. Gradually beat in 1/2 cup of the sugar until soft peaks form.
Beat butter and remaining 1 cup sugar in large bowl on medium-high speed until fluffy and light colored, 2 minutes. On low, beat in flour mixture alternately with milk mixture. Fold in beaten whites, half at a time. Divide between pans.
Bake in 350 degree F oven 20 to 25 minutes, until edges start to pull away from sides. Cool cakes in pans on racks 10 minutes. Turn out onto racks to cool.
Combine sugar, cream of tartar, salt, egg whites and water in top of double boiler. Beat 1 minute; then beat over simmering water 6 minutes, until thick, shiny and firm peaks form. Remove from simmering water. Beat until cool. Beat in vanilla.
Place one cake layer on serving plate. Spread with curd. Top with second layer. Spread top and sides with frosting. Press coconut onto top and sides. Garnish with rose geranium leaf if you wish. Makes 14 servings.