Coconut Layer Cake

I made this cake for my dad's 90th birthday last month. I knew he liked coconut and, therefore, a coconut layer cake seemed to fit the bill for this special occasion. Since I'd never made this before, I perused my cookbooks and the web for recipes and decided to use Bobby Flay's from his Throwdown cookbook based on the same show he had on Food Network as the base. I tweaked it a bit, using ingredient variations from King Arthur Flour's and Cook's Illustrated to come up with this version. The extra rum was my own addition. Go figure...The cake turned out very moist and tender and I was quite happy with how it turned out, and I think dad was, too! This is now my go-to sponge cake (minus the coconut extract) for any dessert that needs a sponge cake. 

What can be made ahead (the day before): 
Coconut Custard
Coconut-Rum Simple Syrup
Cake (but leave out at room temperature overnight)
Buttercream and toasted coconut are best made before assembling cake

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MAKE THE CAKE:
1 tbsp. butter, room temperature (for the pans)

1 cup whole milk, room temperature
5 large egg whites, room temperature
1 large egg, room temperature
1/2 vanilla bean, seeds scraped out and reserved plus 1 tsp. vanilla extract (or 2 tsp. vanilla bean paste)
1 tsp. coconut extract
2 1/4 cups cake flour
1 1/2 cups sugar
1 tbsp. plus 1 tsp. baking powder
1 tsp. iodized salt
12 tbsp. (1 1/2 sticks) unsalted butter, cut into 12 pcs. (slightly cold)

1. Preheat oven to 350F.

2. Butter and flour two 9 x 2" round cake pans; line the bottoms with rounds of parchment (you can buy parchment rounds in some specialty food stores, or just use scissors and cut them out.

3. In a medium bowl, whisk together the milk, egg whites, whole egg, vanillas seeds, vanilla extract, and coconut extract.

4. In the bowl of a stand mixer (use the paddle attachment), add the flour, sugar, baking powder and salt. 

5. With mixer on low speed, add the butter, one piece at a time.

 6. Continue beating until mixture resembles moist crumbs. 

7. Add all but 1/2 cup of the milk mixture and beat on medium until pale and fluffy, about 1 1/2 minutes. 

8. With mixer on low, add remaining 1/2 cup of milk mixture. Increase speed to medium and beat 30 seconds more. Scrape down sides of bowl and mix for another 20 seconds. 

9. Divide batter evenly between the 2 cake pans and smooth tops over with a rubber spatula. 

10. Bake 22-25 minutes, or until toothpick inserted in the middle comes out clean. Let cool in pans on baking rack for 10 minutes. Run a small knife around the sides of the pan and invert the cakes onto a baking rack. Peel off the parchment and let cool completely, about 45 minutes.

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MAKE THE COCONUT CUSTARD*:

3/4 cup whole milk
3/4 cup unsweetened coconut milk
1/2 vanilla bean, seeds scraped out (reserve bean and seeds)
4 large egg yolks
1/3 cup sugar
3 tbsp. cornstarch
1 tbsp. Malibu coconut rum or, for more of a kick, dark rum 
1/2 tsp. vanilla extract

Malibu Coconut Rum, unsweetened coconut milk, and vanilla extract.

Whole vanilla beans.

1. Combine the milk, coconut milk, vanilla bean and vanilla seeds in a medium, non-reactive saucepan and bring to a simmer over low heat. 

2. Whisk the egg yolks, sugar and cornstarch together in a large bowl. 

3. Slowly whisk the warm milk mixture into the egg mixture, then return the mixture back to the saucepan, set over medium heat and bring to a boil.

4. Cook, whisking constantly, until thickened. Scrape the mixture into a bowl, remove the vanilla bean, and whisk in the rum and vanilla extract. 

5. Let cool to room temperature.

6. place some plastic wrap over the top of the custard to prevent a film or skin from forming, then cover the bowl with plastic wrap; refrigerate at least 2 hours, even overnight, until very cold. 

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MAKE THE COCONUT-RUM SIMPLE SYRUP:
1 cup water
1 tbsp. sugar
3 tbsp. Malibu coconut rum
3 tbsp. dark rum

1. Place the water and sugar in a small saucepan and bring to a boil. 

2. Stir until sugar has dissolved and remove from the heat.

3. Let cool to room temperature.

4. Stir in the coconut and dark rum (adjust amounts according to taste - I like my cake boozy, hence the total of 6 tbsp. of the coco and dark rums). 

5. Set aside, covered, until ready to use (ok in the frig).


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MAKE THE BUTTERCREAM:
1 stick unsalted butter, room temperature
2 tbsp. confectioner's sugar
6 tbsp. of coconut custard*

1. Beat the butter and confectioner's sugar in a stand mixer fitted with the paddle attachment until light and fluffy, about 4 minutes. 

2. Add the 6 tbsp. coconut custard and salt and beat until smooth. 

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MAKE THE FILLING:
1 1/3 cups Coconut Custard* (or whatever is left after reserving 6 tbsp. for the buttercream)
3/4 cup cold heavy cream
1/2 tsp. coconut extract

1. Combine the custard (about 1 1/3 cups), heavy cream and coconut extract in a bowl and whip until soft peaks form.

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MAKE THE TOASTED COCONUT:
14-oz. bag of sweetened coconut flakes

1. Preheat oven to 350F.

2. Spread the coconut flakes evenly onto a cookie sheet.

3. Bake 7-8 minutes, stirring occasionally (watch carefully to make sure they don't burn).

4. Remove the cookie sheet immediately from oven when the flakes are lightly browned and scrape them out onto a plate to cool (don't leave them in the pan or else they will continue cooking and burn).

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ASSEMBLE THE CAKE:

1. Use a long serrated bread knife and slice each cake horizontally through the middle to form two layers.

2. Reserve one of the flat bottom layers for the top of the cake.

3. Place another one of the layers on a cardboard round, cut side up, and brush with some of the simple syrup.

4. Spoon 1/3 of the coconut filling onto the cake and spread in an even layer with an offset spatula, leaving a 1/2" border around the edge of the cake.

5. Repeat with 2 more layers. Brush the cut side of the reserved cake layer with the remaining syrup. 

6. Place the layer, cut side down, on top of the cake. Frost the top and sides of the cake with the buttercream (I prefer to use just enough buttercream to cover the cake to keep it light and not overly sweet).

7. Pat the toasted coconut along the sides of the cake and also sprinkle some on top.