- 1 (18.25-ounce) package white cake mix, batter prepared according to package directions
- 1 (12-to 14-ounce) package flaked or grated coconut, divided
- 1 cup (2 sticks) unsalted butter, softened
- 2 cups confectioners' sugar
- 1 (6-ounce) package white baking bars, melted
- Mix 2 cups coconut into cake batter and bake according to package directions for two 9-inch round layers; let cool completely.
- In a large bowl, with an electric beater on medium speed, beat butter, confectioners' sugar, and melted white baking bars until fluffy and doubled in size. Add remaining coconut and mix until thoroughly combined.
- Place one cake layer upside-down on a serving platter and frost top. Place second layer over first and frost top and sides. Cover loosely and chill at least 2 hours before serving.