Coconut Custard Filling
1 1/4 cups milk
1 1/4 cups coconut milk, shaken well
5 egg yolks
3 tablespoons cornstarch
1/2 cup granulated sugar
1 teaspoon vanilla extract
1 1/3 cups shredded coconut

In a heavy medium-size saucepan, warm milk and coconut milk. Place a strainer over a large bowl set in a larger bowl of ice. In a bowl with a pouring spout, beat the yolks, cornstarch and sugar together until smooth and ribbon-like, about 1 minute. Whisk half the hot milk into the yolks, then pour back into the remaining milk and slowly bring to a boil. Boil, whisking constantly, for 1 minute. Custard will thicken quickly. Immediately strain. Stir in vanilla extract, and keep stirring to cool.

Spread shredded coconut on a cookie sheet. Toast at 350 degrees F about 15 minutes, or until lightly browned. Reserve 1/3 cup for top of cake. Add remaining coconut to custard. Press plastic wrap directly over the surface of the custard to prevent skin from forming, and chill for about 2 hours.

Cake
2 2/3 cups cake flour
1 1/2 teaspoons baking powder
1/2 teaspoon salt
1 cup butter, in pieces
1 3/4 cups granulated sugar
4 egg yolks
1 1/2 teaspoons vanilla extract
1 cup coconut milk
1/2 cup shredded coconut
4 egg whites

Grease 2 (9-inch) cake pans. Line with wax paper traced to fit the bottoms of the pans. Preheat oven to 350 degrees F. Sift dry ingredients together 3 times. In another bowl, cream butter with sugar until fluffy. Add yolks, one at a time, beating until each one is incorporated. Add vanilla extract. Alternately add coconut milk and dry ingredients to butter-egg mixture. Fold in the 1/2 cup shredded coconut. Beat egg whites to stiff, glossy peaks, then gently fold into batter. Pour batter into the prepared pans. Bake 25 minutes. Cool in pans set on racks for 10 minutes. Run a knife around pans and turn cakes out on racks to cool completely.

Coconut Drizzle
1 cup coconut milk
1 teaspoon granulated sugar

Mix together coconut milk and sugar and pour liquid over cake layers before frosting.

Swirl Frosting
1/2 cup water
1 cup light corn syrup
1 1/2 cups granulated sugar
3 egg whites

Bring water, corn syrup and sugar to a boil over medium-high heat. Cook until mixture is clear and can spin a thread (230 degrees F to 234 degrees F). If sugar browns, it will become too caramelized and frosting will be stiff.

Meanwhile, beat egg whites to stiff peaks. Adding the hot sugar mixture in a slow stream, beat it into the whites, and keep beating about 5 minutes, until glossy, stiff peaks form and frosting is cool.

To assemble, trim any hardened surfaces from cakes, then halve them horizontally. Brush Coconut Drizzle on the layers with a pastry brush. Fill and frost cake with Swirl Frosting. Sprinkle reserved toasted coconut on top of cake.