01 -
Preheat oven to 175°C. Butter three 20 cm round baking pans, line bases with parchment paper, butter again, and dust lightly with flour.
02 -
In a medium bowl, whisk together sifted cake flour, baking powder, baking soda, and salt. Set aside.
03 -
In a stand mixer with paddle attachment, cream the butter and sugar on medium-high speed until light and fluffy, about 5 minutes. Scrape down bowl as needed.
04 -
Beat in eggs one at a time, followed by egg whites, mixing after each addition. Add sour cream, vanilla, and coconut extracts. Mix well.
05 -
With mixer on low, add dry ingredients and buttermilk in three alternating additions, beginning and ending with dry. Mix just until combined; do not overmix.
06 -
Using a spatula, gently fold in the shredded coconut until evenly distributed.
07 -
Divide batter evenly among prepared pans. Bake 35–45 minutes or until a toothpick inserted in the centre comes out clean.
08 -
Cool cakes in pans on a wire rack for 10–15 minutes. Turn out onto wire rack and cool completely before frosting.
09 -
Wipe stand mixer bowl and whisk with vinegar or lemon juice to remove grease and ensure egg whites whip properly.
10 -
Combine egg whites, sugar, and salt in stand mixer bowl. Place over a saucepan of simmering water and whisk until mixture is hot to the touch and sugar has dissolved, about 3 minutes.
11 -
Remove bowl from heat and dry bottom. Whisk on medium-high until meringue holds stiff peaks and is cooled, about 10–15 minutes.
12 -
Switch to paddle attachment. With mixer on medium, add butter piece by piece, allowing each to incorporate. Scrape bowl as needed. Add coconut milk powder and whip on high until thick and fluffy, about 5 minutes.