1. Preheat oven to 350°. Grease and flour 2 (9-inch) round pans. Line bottoms of pans with parchment paper. Lightly grease parchment paper.
2. Melt chocolate in a microwave-safe bowl at HIGH 1 1/2 minutes or until smooth, stirring at 30-second intervals.
3. Beat butter and sugars at medium speed with a heavy-duty electric stand mixer until well blended (about 3 minutes). Add eggs, 1 at a time, beating just until blended after each addition. Add melted chocolate, beating just until blended.
4. Sift together flour, baking soda, and salt. Gradually add to chocolate mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. (Mixture will be thick.)
5. Stir vanilla into hot coffee. Gradually add coffee mixture to batter in a slow, steady stream, beating at low speed just until blended. Pour batter into prepared pans.
6. Bake at 350° for 38 to 42 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on a wire rack 10 minutes. Remove from pans to wire rack, and let cool completely (about 1 hour).
7. Spread Whipped Ganache Filling between layers, spreading to edges of cake and leveling with an offset spatula. Gently press top cake layer down, pressing out a small amount of Ganache Filling from between layers, and spread filling around sides of cake, filling in any gaps between layers. Spread Seven-Minute Frosting over top and sides of cake. Swirl frosting using back of a spoon, if desired. Top with Candied Oranges. Garnish, if desired.