Preheat oven to 350°F (175°C). Grease and flour two 9-inch round baking pans.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
Combine the flour, baking powder, baking soda, and salt; gradually beat into the creamed mixture.
Dissolve the cocoa in boiling water; add to the batter along with the sour cream. Beat until smooth.
Pour the batter into the prepared pans. Bake for 25 to 30 minutes in the preheated oven, until a toothpick inserted into the center of the cake comes out clean.
Allow cakes to cool for 10 minutes before removing from pans to cool completely.
In a medium bowl, blend the coffee, cream, sugar, and espresso powder until thick. Spread between the two layers of the cake.
Spread the fudge sauce over the top and sides of the cake. Sprinkle with chopped nuts, if desired.
Interesting Facts
Mocha is a flavor derived from the combination of chocolate and coffee.
Mocha Fudge Cake is a perfect dessert to serve at a dinner party.
This cake is best served chilled, as the flavors will intensify.