Position oven rack in the center (or just below center) of the oven. Preheat oven to 350°F [175°C]. Grease and flour three round cake pans. Line pans with parchment paper for easy release and clean-up. NOTE: 8" or 9" cake pans will work for this cake. (They must, however, all be the same size!)
Measure sifted cake flour, baking powder, and salt; sift together three times. Set aside.
Combine sour cream and coconut milk in a small bowl and set aside.
Using an electric mixer with a large mixing bowl, cream butter and sugar together until light and fluffy. Add coconut extract and mix to combine. Add flour mixture alternately with coconut milk and sour cream mixture, beating after each addition. Remove bowl from mixer and set aside.
[DO NOT begin this step until you have completed the previous step.] In a medium mixing bowl, beat egg whites until foamy. Add 1/2 cup sugar gradually, beating until meringue will hold soft peaks.
[Do this step by hand. Do not use a mixer.] Carefully fold beaten egg whites into batter.
Pour batter evenly into the three prepared cake pans. Bake layers in preheated oven: 22-25 for 9" cake pans / 25-30 minutes for 8" cake pans - or until a toothpick or skewer comes out clean. (If your oven cooks unevenly, carefully rotate pans on rack at the 15-minute mark.)
Allow cakes to cool in their pans over wire rack for 10 minutes. Carefully tap out onto wire rack to cool completely. Wrap and chill layers in refrigerator for at least an hour (or up to a week if you need to).
Using an electric mixer, beat butter on medium-high until light and fluffy. Add coconut and vanilla extracts and salt and mix to thoroughly combine.
Slowly add powdered sugar, mixing well after each addition.
Add coconut milk, one tablespoon at a time time, beating on medium-high until fully incorporated.
This website provides approximate nutrition information for convenience and as a courtesy only. You are solely responsible for ensuring that any nutritional information provided is accurate, complete, and useful.