Preheat oven to 350F
Butter and flour two 9-inch round baking pans.
In a large mixing bowl, whisk together sugar, flour, cocoa, baking soda, baking powder and salt.
Add eggs, buttermilk, coffee, oil and vanilla.
Using an electric mixer, beat on medium speed for about 2 minutes. You should have a thin batter.
Pour batter evenly into prepared pans.
Bake for 30 to 35 minutes, or until toothpick inserted in center comes out clean.
Cool 10 minutes; remove cakes from pans to wire racks.
Cool completely before frosting.
!PREPARE THE FROSTING
Place chopped chocolate in a medium mixing bowl; set aside.
Place whipping cream and butter in saucepan and cook over medium heat to just a boil.
Pour cream mixture over chocolate; whisk vigorously until chocolate is melted and smooth.
Cover and refrigerate for an hour.
Remove from fridge and stir; refrigerate about 1 more hour or until spreading consistency.
Spread about 1/4 to 1/3 of frosting on one cake layer; top with the other cake layer and spread frosting on top and sides of cake.
Cut and Serve.