CHOCOLATE BIRTHDAY CAKE AND DOUBLE CHOCOLATE SOUR CREAM FROSTING

Steps:

• Preheat the oven to 325°F.
• Grease and flour the insides of two 14-14.5 ounce cans.
• Place the cans on a baking sheet, and set aside.
• Whisk the buttermilk, egg yolk, and vanilla together in a small bowl.
• Gradually pour the melted butter into the buttermilk mixture, whisking constantly.
• Sift the flour, cocoa powder, baking soda, and salt into a medium-size mixing bowl; add sugar, and then whisk to blend well.
• Add the buttermilk mixture and whisk just until the dry ingredients are moistened.
• Divide the batter between the prepared cans.
• Bake the cakes until a toothpick inserted into the center comes out clean, 25 to 30 minutes.
• Place the cans to a wire rack to cool for 15 minutes.
• Run a knife around the edge of each can and invert them to release the cakes.
• Turn the cakes upright and let them cool completely on the rack.
• Meanwhile, make the frosting: Place chocolate in the top of a double boiler set over simmering water, and heat, stirring occasionally, until melted. (May also do this in the microwave.).
• Let the chocolate mixture cool for 5 minutes. Then add the sour cream, vanilla, and salt, and whisk to blend well.
• Let the frosting cool to room temperature, stirring it occasionally.
• When frosting and cakes have cooled, cut each cake in half horizontally.
• Spread a layer of frosting about 1/2 inch thick on the cut side of one cake half, then stack the other half on top of it.
• Frost the top and sides of the cake.
• Repeat with the remaining cake and frosting.
• Store the cakes in the refrigerator in an airtight container, bringing them back to room temperature before serving.