Heat oven to 350°F. Grease and flour three 9-inch round cake pans.
In a glass bowl, melt butter and chocolate together in microwave on high until melted and smooth, 1 to 1-1/2 minutes, stirring halfway through. Set aside. On low speed, mix flour, sugar, cocoa, baking soda, baking powder and salt in a large bowl until blended.
Add sour cream, eggs, 1 cup water, chocolate mixture and vanilla; beat 30 seconds on low, until dry ingredients are moistened. Increase to medium; beat 2 minutes. Pour into prepared pans.
Bake at 350°F for 40 minutes or until cake layers spring back when pressed.
Cool layers in pans on rack 10 minutes. Remove cakes to rack to cool.
In a small glass bowl, melt chocolate in microwave on high for 1 minute. Stir until smooth. Set aside. Beat shortening, butter, sour cream, milk, vanilla, salt, 1 cup of the sugar and the cocoa powder in a medium-size bowl until creamy. Gradually beat in remaining sugar and melted chocolate until thick and smooth.
Place a cake layer on pedestal. Spread with about 2/3 cup frosting. Top with second layer; spread with about 2/3 cup more frosting. Top with remaining layer. Frost top and sides, swirling decoratively. Garnish with chocolate curls and berries.