For citrus curd
6 large egg yolks
¾ cup sugar
1 stick (1/2 cup) cold unsalted butter, cut into pieces
¼ cup fresh lemon juice
¼ cup fresh lime juice
1 teaspoon freshly grated lemon zest
1 teaspoon freshly grated lime zest
For cake
3 cups sifted Swans Down Cake Flour
1 tablespoon baking powder
¾ teaspoon salt
1 ¼ cup whole milk
1 ½ teaspoons vanilla
¾ cup sweetened flaked coconut
2 ½ sticks (1 ¼ cups) unsalted butter, softened
1 ¾ cup sugar
5 large eggs
½ cup sweetened flaked coconut
For frosting
2 large egg whites
1 ½ cups sugar
5 tablespoons cold water
2 teaspoons light corn syrup
¼ teaspoon cream of tartar
½ teaspoon vanilla
Topping
1 cup sweetened flaked coconut

Make curd: In a heavy saucepan whisk together yolks, sugar, butter, lemon juice and lime juice. Cook over moderately low heat, whisking constantly, about 5 minutes, or until mixture just reaches a boil. Strain curd through a fine sieve into a bowl and stir in zest. Chill curd, its surface covered with plastic wrap, at least 4 hours and up to 2 days ahead. Make frosting: In top of a double boiler off heat or in a large metal bowl with a hand-held electric mixer beat together all frosting ingredients except vanilla until combined. In double boiler or in bowl set over a saucepan of boiling water (do not let pan or bowl touch water) beat mixture on high 7 minutes, or until it holds stiff glossy peaks. (This may take longer in humid weather.) Remove from heat and add vanilla. Beat mixture until cool, about 3 minutes (do not overmix). Spread frosting evenly over top and sides of cake and coat with coconut. Make cake: In bowl whisk together flour, baking powder and salt. In a small bowl stir together milk, vanilla and coconut. In a large bowl with an electric mixer beat butter on medium speed 1 minute and gradually beat in sugar until light and fluffy, about 3 minutes. Beat in eggs, 1 at a time, beating well after each addition. Reduce speed to low and add flour mixture in batches alternately with milk mixture, beginning and ending with flour mixture and scraping bowl occasionally, until batter is just combined (do not overbeat). Divide batter among pans and smooth tops. Bake layers in middle and lower thirds of oven (do not put one pan directly underneath another) until a tester inserted in center comes out clean, about 30 minutes. Cool cake layers in pans on racks 10 minutes before turning out onto racks. Remove paper from cakes and cool completely. Cake layers may be made 1 day ahead and kept, wrapped in plastic wrap, in an airtight container in a cool dry place. Place 1 cake layer on a cake plate, dome side down, and spread evenly with about half of curd. Sprinkle with ¼ cup coconut and chill 15 minutes. Repeat layering in same manner with another cake layer, remaining curd, and remaining ¼ cup coconut and top with remaining cake layer, dome side up. Chill cake 15 minutes. Preheat oven to 350 degrees F. Line bottoms of three 9- by 2-inch buttered cake pans with parchment paper. Butter paper and flour pans, knocking out excess.