Mix the flour, baking powder, and salt in a bowl. Place egg yolks and sugar in a stand mixer bowl and mix well.
Then add coconut milk, mayonnaise, coconut, buttermilk, and vanilla extract. Add dry ingredients to the batter and mix well.
Beat the egg whites and sugar with a hand mixer in a bowl. The meringue is ready.
Now, layer the cakes and fill the meringue in between the layers. Cover the top and sides of the cake with meringue. Chill the cake in the refrigerator for 30 minutes. The coconut cake is ready.