Measure flour carefully, preferably with a digital scale, to prevent dense cake., Ensure butter, cream cheese, egg whites, and sour cream are at room temperature for silky batter and frosting., Beat butter and sugar until light and fluffy; whip egg whites until just foamy before folding in gently for tender rise., Alternate adding dry ingredients and coconut milk/sour cream mixture; start and end with dry ingredients to avoid dryness., Use finely shredded unsweetened coconut in batter and larger flakes for decoration to avoid chewy bits., Prepare pans with greasing, spraying, and parchment rounds for easy cake release., If frosting is too thin, add confectioners’ sugar gradually (max 1/4 cup each time) to thicken without over-sweetening., Press shredded coconut firmly onto cake sides for better adhesion., If making two layers instead of three, bake layers for 28-30 minutes and test doneness with a toothpick., Best stored covered in the refrigerator due to cream cheese frosting; consume within 24 hours for optimal flavor and texture., Can freeze unfrosted cake layers wrapped tightly for up to 3 months; thaw overnight in fridge before frosting and assembling., Freezing assembled cake may alter texture of shredded coconut; if freezing, wrap well and thaw slowly in fridge.