Combine these dry ingredients, set aside.
Combine and mix, set aside.
Melt the chocolate in a double boiler on low heat. Cream the butter, add the sugar to this and beat rapidly until fluffy. Beat the egg yolks into this mixture one at a time. Next add the melted chocolate and beat rapidly for 30 seconds. Continue to beat rapidly and at 15 second intervals, add 1/2 cup of the cake flour mixture and then 1/2 cup of the sour dough/coffee mixture. Proceed until all three mixtures are thoroughly combined and the batter is smooth. Set aside.
Beat the egg whites (make sure the beaters are clean) until they form peaks.
Fold the beaten egg whites gently into the cake batter. The batter will be pretty solid, but don't let this worry you, just keep folding until it is evenly incorporated. Pour the completed cake batter into three cake pans which have been lined on the bottom with waxed paper and buttered on the sides. Bake in a preheated 350 degree oven for 30-40 minutes. When the cake has shrunk away from the sides of the pan and springs back when lightly touched at the center, it is done. Remove the cake for the oven and cool.
Ganache to use as mortar between the layers:
Heat cream and sugar a gentle simmer for 1 minute and pour over chocolate.
Let sit 2 minutes and whisk until smooth. Then whisk in butter, then vanilla. Pour ganache onto a bowl, cover and chill it in the refrigerator about 30 minutes, until it is beginning to stiffen and about 70 degrees. Then beat it with an electric mixer until lighter in color and density (about 1 minute). Divide and spread gently between cake layers. Refrigerating stiffens it so the layers will not squish or slide.
Icing for top and sides of cake: (this recipe is big-ish)
Start with all ingredients at room temperature (except whipped cream). Melt the chocolate in a double boiler over hot, not boiling, water. Make sure the chocolate is fully melted, so that it doesn't harden and chunk up before incorporating the whipped cream. Meanwhile, beat the sugar, cream cheese, vanilla, cinnamon, and salt together until creamy; beat in the egg yolk; next, stir in the melted chocolate; finally fold in the whipped cream. It might take a lot of folding to fully incorporate the whipped cream. Cover and refrigerate until thick, about 1 hour. Frost.