All-in-One Chocolate Cake

Preparation

1. Step 1

   For cake: heat oven to 350 degrees. Butter sides of two 8-inch cake pans, and line bottoms with parchment paper. In the bowl of a food processor fitted with a knife blade, combine flour, sugar, baking powder, baking soda, cocoa powder, butter, eggs, vanilla and sour cream. Process to make a smooth, thick batter.

2. Step 2

   Using a rubber spatula, divide batter between pans, and smooth tops. Bake until a cake tester inserted in center comes out clean, 25 to 35 minutes; do not overbake. Transfer to a wire rack to cool for 10 minutes before removing from cake pans.

3. Step 3

   For frosting: Combine chocolate and butter in a large heat-proof bowl, and heat until melted in a microwave oven or over a pan of simmering water. Remove from heat, and allow to cool for 5 minutes. Stir in corn syrup, sour cream, and vanilla. Whisk in confectioners' sugar until very smooth. Frosting should be thick and spreadable. If necessary, add a teaspoon or two of boiling water to thin it, or additional sifted confectioners' sugar to thicken.

4. Step 4

   Cut four strips of waxed or parchment paper, and place them side by side on a cake plate, covering the surface. Place one cake layer domed-side down on plate.

5. Step 5

   Spoon about a third of the frosting onto center of cake, and use a knife or a spatula to spread it evenly. Place the other cake on top, domed side up. Spoon another third of frosting on top of cake, spreading to make swirls or a smooth finish. Spread sides of cake with remaining frosting, and allow to sit for a few minutes until set. Carefully remove paper strips. Place cake under glass or in an airtight container, and set aside in a cool place until serving.