1. Heat oven to 350 degrees F. Coat two 9-inch round cake pans with nonstick spray.
2. Cake. In bowl, whisk flour, cocoa, baking soda and salt. In large bowl, beat butter until smooth. Add brown sugar; beat until blended. Beat in eggs, one at a time, and vanilla. On low, alternately beat in flour mixture and buttermilk, beginning and ending with flour. Spread into prepared pans.
3. Bake at 350 degrees F for 30 minutes or until toothpick inserted in centers comes out clean. Cool in pans on wire rack for 10 minutes. Invert cakes directly onto racks; cool completely. While the cakes cool, make the frosting.
4. Place one cake layer on pedestal. Spread top with 1 cup frosting and 1/2 cup coconut. Add second layer. Spread frosting on top and side of cake. Press remaining 2 1/2 cups coconut into frosting. Garnish with raspberries and mint, if desired.
1. Place confectioners' sugar in a large bowl. Beat in boiling water. Add butter and cream cheese, beating well on medium-high speed after adding each piece. Beat in extract. Refrigerate until firmer consistency, 30 minutes to 1 hour.