SERVING: 10 to 12
For the cake:
Butter, for greasing baking pans
1 1/2 cups all-purpose flour
1 cup sugar
1 teaspoon baking powder
1/2 teaspoon baking soda
1/3 cup best-quality cocoa powder
6 ounces (1 1/2 sticks) unsalted butter, at room temperature
2 large eggs, at room temperature
2 teaspoons vanilla
3/4 cup sour cream, at room temperature
For the frosting:
6 ounces good quality semi-sweet chocolate, broken into small pieces
3 ounces (3/4 stick) unsalted butter
1 tablespoon light corn syrup
1/2 cup sour cream
1 teaspoon vanilla
2 1/2 cups confectioners’ sugar, sifted
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. Using a rubber spatula, divide batter between pans and smooth tops. Bake for about 25 to 30 minutes until a cake tester insert in the centre comes out clean; do not over-bake. Transfer to a wire rack to cool for 10 minutes before removing from cake pans.
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 five 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. 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 a plate.
5. Spoon about a third of the frosting onto cake’s centre 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.