Chocolate Layered Cake

Cake

2 cups flour
1 teaspoon baking soda
1/2 teaspoon salt
1 cup butter, softened
1 cup sugar
1 cup firmly packed light brown sugar
4 large eggs, at room temperature
6 ounces (1/2 bag) unsweetened chocolate, melted
3/4 cup buttermilk
1 teaspoon vanilla extract
1/4 cup sour cream

Preheat oven to 350°. Grease and lightly flour two or three 9-inch round baking pans. Line the bottoms.
Sift together flour, baking soda, and salt. Set aside.
Mix butter and sugars until fluffy. Add eggs one at a time, beating well after each. Add chocolate, and mix until well incorporated. Add dry ingredients in three parts, alternating with buttermilk and vanilla. Beat until smooth. Stir in sour cream.
Divide batter equally and pour into prepared pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Cool in pans for 10 minutes. Then, remove from pans and cool completely on wire racks.

Cream Cheese Frosting

1/3 cup butter, softened
3 ounces cream cheese, softened
3 & 3/4 cups powdered sugar
3 tablespoons heavy cream
1/2 teaspoon vanilla extract
1/8 teaspoon salt

Mix butter and cream cheese with a wooden spoon until blended. Add 2 cups of sugar, half of the heavy cream, and salt. Beat until smooth. Add remaining sugar, cream, and vanilla. Mix until smooth, but do not overmix. If frosting is too thick, add a few drops of heavy cream.
Spread frosting between cake layers.

Chocolate Cream Cheese Frosting

2/3 cup butter, softened
16 ounces cream cheese, softened
1/2 cup cocoa powder
3 cups powdered sugar
2 tablespoons sour cream
1 teaspoon vanilla extract

Mix butter and cream cheese until smooth. Stir in cocoa powder. Add sugar in three portions, alternating with sour cream. Beat until smooth and creamy. Stir in vanilla extract.
Spread frosting on top and sides of cake.
Place frosted cake in refrigerator to allow it to set.