Makes an 8-inch round layer cake
For the cake:
3 sticks (1 ½ cups; 336g) unsalted butter, room temperature, plus more for pans
3 ½ cups (450g) all-purpose flour, plus more for pans
4 teaspoons (16g) baking powder
1 ¾ teaspoons (5g) kosher salt
1 cup packed sweetened shredded coconut
2 2/3 cups (547g) sugar
4 large whole eggs plus 4 large whites (215g eggs, 130g whites)
1 tablespoon (12g) pure vanilla extract
1 ½ cups (164g) unsweetened coconut milk
For the frosting:
9 large egg whites
2 1/24 cups sugar
3 tablespoons corn syrup
1/3 cup cold water
¼ teaspoon cream of tartar
2 teaspoons vanilla extract
Sweetened shredded coconut, for garnish
1. Make the cake: Preheat oven to 350°F. Butter two 8-inch round pans, line with parchment paper leaving an overhang on two sides. Butter parchment. Dust with flour, tapping out excess. In a large bowl, whisk together flour, baking powder, and salt. Pulse shredded coconut in a food processor until finely chopped. Stir chopped coconut into the flour mixture.
2. In the bowl of your Martha Stewarr 5.3qt Stand Mixer fitted with the beater attachment, beat butter and sugar on medium high speed (6 to 8) until light and fluffy. Gradually, add the whole eggs, egg whites and vanilla; beat until combined. With the mixer on low speed (2 to 4), add the flour mixture, alternating with the coconut milk, beginning and ending with the flour; beat to combine after each addition
3. Divide batter between prepared pans smoothing top with an offset spatula. Bake, rotating pans halfway through, until cakes are golden brown and a cake tester inserted in the centers comes out clean, about 35 minutes. Let cool in pans on wire racks for 15 minutes. Lift out of pans and cool completely. Cakes can be made ahead up to this point and kept wrapped well, at room temperature for up to 2 days, or frozen for up to 3 months.
4. Trim domed tops of cakes. Split each cake in half horizontally creating 4 layers.
5. Make the icing; Combine egg whites, sugar, water and cream of tartar in the bowl of an electric mixer set over but not in a pot of simmering water. Whisk constantly until a thermometer inserted in mixture reads 160°F about 2 minutes. Attach bowl to mixer and beat with whisk on high until glossy and voluminous, and completely cooled, about 8 minutes. Beat in vanilla. Use immediately.
6. Place a cake layer bottom side down on a cake plate. Spread with about 1 ½ cups icing. Top with a second layer. Repeat finishing with a bottom side up. Spread icing generously over top and sides of cake. Garnish cake with coconut.
