Coconut buttercream can work well on layer cakes if you control the milk content and keep the frosting cold enough to hold its shape. Reduced coconut milk, whipped butter, and powdered sugar create a smooth icing that spreads cleanly, pipes neatly, and firms up after chilling.
Essential Concepts
Reduce coconut milk for stability.
Use butter and powdered sugar for structure.
Chill between coats.
Fix looseness with sugar, graininess with more whipping.
