I found this on Ghirardelli's website. It is my families most favorite chocolate cake of all time. When I make this for my husband I can have anything I want!! This sends him into chocolate euphoria. Eat at your own risk! ;)
Grease the bottoms of two 8- or 9-inch round cake pans, and line with parchment paper. I've also been "lazy" and used one 9x13 cake pan.
In a large mixing bowl, combine the four, ground chocolate, granulated sugar, baking soda, cream of tartar, and salt.
Add 1 cup of the buttermilk and 1 cup of butter.
Beat on medium speed for 2 minutes.
Add the remaining ½ cup of buttermilk, the eggs, and 1 teaspoon of vanilla extract.
Divide the batter between the prepared cake pans.
Bake for 30 to 45 minutes, or until a tester comes out clean when inserted into the cake’s center.
Cool on a wire rack for 10 to 15 minutes.
Remove cakes from the pans, discard the parchment paper, and transfer them to the wire rack to cool completely.
Melt the chocolate (broken into pieces) in a double boiler over hot, but not boiling, water. Stir occasionally until the chocolate is melted and smooth.
Dissolve the instant coffee granules in the boiling water.
Stir coffee mixture into the chocolate then remove from heat and set aside. NOTE: this mixture does have a tendency to seize up, but don’t worry, when it’s added to the rest of the frosting and mixed in, it comes out just fine.
In a large mixing bowl, beat the 2/3 cup butter until fluffy.
Gradually add the confectioners’ sugar, milk, and vanilla extract, mixing until smooth.
Add the melted chocolate and mix until well combined.