Coconut Layer Cake from Cook’s Illustrated
2 ¼ cups plain cake flour, sifted, plus more for dusting the pans
1 large egg, plus 5 large egg whites
¾ cup cream of coconut
¼ cup water
1 tsp coconut extract
1 tsp vanilla
1 cup sugar
1 T baking powder
¾ tsp salt
12 T (1 ½ sticks) unsalted butter, softened but still cool, cut into 12 pieces
2 cups packed sweetened shredded coconut
Coconut Buttercream
4 large egg whites
1 cup sugar
Pinch salt
1 lb (4 sticks) unsalted butter, softened up still cool, each stick cut into 6 pieces
¼ cup cream of coconut
1 tsp coconut extract
1 tsp vanilla
For the Cake: Adjust on oven rack to the lower-middle position and heat the oven to 325 degrees. Grease two 9-inch round cake pans and just with flour, tapping out the excess.
2. Beat the whole egg and egg whites in a large liquid measuring cup with a fork to combine. Add the cream of coconut, water, coconut extract, and vanilla and beat with a fork until thoroughly combined.
3. Mix the flour, sugar, baking powder, and salt in the bowl of a standing mixer at the lowest speed to combine, about 30 seconds. With the mixer still running at the lowest speed, add the butter, one piece at a time, then beat until the mixture resembles coarse meal, with butter bits no larger than small peas, 2 to 2 ½ minutes.
4. With the mixer still running, add 1 cup of the egg mixture to the flour and butter mixture. Increase the speed to medium-high and beat until light and fluffy, about 45 seconds. With the mixer still running, add the remaining 1 cup liquid in a steady stream (this should take about 15 seconds). Stop the mixer and scrape down the bowl with a rubber spatula, then beat at a medium-high speed to combine, about 15 seconds. (The batter will be thick.)
5. Divide the batter between the cake pans and level with a rubber spatula. Bake until the cakes are deep golden brown, have pulled away from the sides of the pans, and a toothpick or thin skewer inserted into the center of the cakes comes out clean, about 30 minutes (rotate the pans from front to back after about 20 minutes). Do not turn off the oven.
6. Cool the cakes in the pans on wire racks for about 10 minutes, then loosen the cakes from the sides of the pans with a paring knife, invert the cakes onto the racks, and reinvert them so the top sides face up; cool to room temperature.
7. To Toast the Coconut: While the cakes are cooling, spread the shredded coconut on a rimmed baking sheet; toast in the oven until the shreds are a mix of golden brown and white, 15 to 20 minutes, stirring 2 or 3 times. Cool to room temperature.
8. For The Buttercream: Combine the egg whites, sugar, and salt in a mixing bowl; set the bowl over a saucepan containing 1 ½ inches of barely simmering water. Whisk constantly until the mixture is opaque and warm to the touch and registers 120 degrees on an instant-read-thermometer, about 2 minutes. Remove from the heat.
9. Using a standing mixer, beat the whites at high speed until they are barely warm (about 80 degrees), glossy, and sticky, about 7 minutes. Reduce the speed to medium-high and beat in the butter, one piece at a time. Beat in the cream of coconut, coconut extract, and vanilla. Stop the mixer and scrape the bottom and sides of the bowl with a rubber spatula. Continue to beat at medium-high speed until well combined, about 1 minute.
10. To Assemble The Cake: Cut the cakes in half horizontally so that each cake forms 2 layers. Assemble and frost the cake, sprinkling the top of the cake with the toasted coconut, then press the coconut into the sides of the cake with your hand, letting the excess fall back onto a baking sheet.