Preheat oven to 350°F
Grease three eight inch cake pans. Line bottom with wax paper. Grease and flour paper.
Heat milk and coffee in a small sauce pan until bubbles form around edge. Add to cocoa and whisk until smooth. Whisk in sour cream. cool.
In medium bowl, combine flour, baking soda, baking powder, and salt. Beat butter in mixing bowl until light. Gradually beat in sugar until light and fluffy. Beat in eggs one at a time. Add vanilla. At low speed gradually beat in dry ingredients alternately with Chocolate mixture, beginning and ending with dry ingredients. Beat at medium speed 2 minutes. Pour into prepared pans. Bake 25 minutes, until top springs back when lightly when lightly touched. Cool pan on wire rack ten minutes. Invert cakes onto rack. Remove paper and cool completely, right side up.
Creamy Fudge Frosting:.
Heat Chocolate, sugar and cream, stirring constantly, in saucepan over medium heat until smooth. Remove from heat; stir in vanilla. Transfer to mixer bowl, and place in larger bowl of ice water. Let stand, stirring occasionally, until cold and thick. Remove from ice bath. Gradually beat in butter at high speed; beat until fluffy and stiff enough to hold it's shape.
Place 1 layer on cake plate and spread with 3/4 cup frosting. Top second with second layer and another 3/4 cup frosting. Spread Top and sides with remaining frosting. Makes twelve servings.