Place oven rack in lowest position; heat oven to 350°F. In large glass or metal bowl, combine all cake ingredients at low speed until moistened. Beat 1 minute at medium speed. Do not overbeat; batter may be thin. Pour batter into ungreased 10-inch tube pan.
Bake at 350°F. on lowest oven rack for 35 to 45 minutes or until top crust is deep golden brown and cracks are very dry. Cool upside down on glass bottle or heatproof surface for 1 hour or until completely cool. Remove cooled cake from pan.
In large bowl, combine all frosting ingredients; beat until stiff peaks form. Frost sides and top of cake. Garnish with grated chocolate. Store in refrigerator.