Set 1 cake layer right side up on a wire rack and spread with half of the chilled ganache. Cover with a second layer and the remaining chilled ganache. Top with the third cake layer, smooth side up; press down gently. Pour half of the reserved ganache on top and spread it evenly, letting it drip slightly down the sides. Pour on the remaining ganache and smooth the top and sides. Transfer the cake to a cake plate. Refrigerate for 15 minutes, then press the remaining coconut onto the sides of the cake. Garnish with chocolate curls and serve or, for best results, refrigerate the cake overnight.