Choco-nilla Cake

Ingredients (Vanilla Cake)
1 cup (8 ounces) sour cream or plain yogurt (full-fat is best)
2 large eggs
1 cup (7 ounces) sugar
1/2 teaspoon salt
1 ¾ teaspoons baking powder
1/3 cup (2 3/8 ounces) vegetable oil
2 teaspoons vanilla extract
2 cups (8 ½ ounces) King Arthur Unbleached All-Purpose Flour

Ingredients (Chocolate Cake)
1 1/3 cups (9 3/8 ounces) sugar
1 1/3 cups (5 3/8 ounces) King Arthur Unbleached All-Purpose Flour
2 tablespoons (3/8 ounce) Instant ClearJel® or cornstarch (1/2 ounce)
1/2 cup (1 1/2 ounces) Double-Dutch Dark Cocoa or Dutch-process cocoa
1 1/4 teaspoons baking powder
2 teaspoons espresso powder
1/4 teaspoon baking soda
1/2 teaspoon salt
3 large eggs
1/2 cup (3 ½ ounces) vegetable oil
2 teaspoons vanilla extract
3/4 cup (6 ounces) water

Ingredients (Filling)
12 ounces (2 cups) chopped semisweet chocolate or chocolate chips
6 ounces cream (light, whipping, or heavy) or milk, or a combination*
flavors of your choice (see filling directions below)

*Hint: Since you need 4 ounces of cream for the icing, and you’ll most likely buy an 8-ounce container, use 4 ounces cream in the filling supplemented with 2 ounces of milk.

Ingredients (Icing)
8 ounces (1 1/3 cups) chopped semisweet chocolate or chocolate chips
4 ounces cream (light, whipping, or heavy)

Directions (General)

1. Preheat the oven to 350°F. 

2. Lightly grease two 9" x 2" round cake pans: one for the vanilla cake, one for the chocolate. If desired, line with parchment, and grease the parchment; this will ensure the cakes turn out intact.

Directions (Vanilla Cake)
3. Whisk together the yogurt or sour cream, eggs, sugar, salt, baking powder, vegetable oil, and vanilla.  

4. Stir in the flour, mixing till smooth.
5. Pour the batter into one of the prepared pans.  

6. Bake the cake for 35 to 45 minutes, until the cake is beginning to brown on top. It may crack slightly; that’s OK.  

7. Remove the cake from the oven, and after 10 minutes turn it out of the pan onto a rack to cool.

Directions (Chocolate Cake)
8. Whisk together the dry ingredients. 

9. Add the eggs, oil, and vanilla, beating until smooth. 

10. Gradually add the water, beating until smooth. 

11. Pour the batter into the prepared pan. 

12. Bake the cake for about 35 minutes, or until a cake tester inserted into the center comes out clean. 

13. Remove the cake from the oven, and after 10 minutes turn it out of the pan onto a rack to cool. 

14. Divide the cooled cakes in half horizontally, to make four round layers. Place one vanilla layer on a serving plate.

Directions (Filling)

15. Combine the chocolate and cream in a microwave-safe bowl, and heat until the cream is very hot, and the chocolate very soft. 

16. Stir to melt the chocolate completely, reheating very briefly if necessary. If desired, flavor with 3 tablespoons liqueur (Kahlua, Frangelico, etc.). 

17. Spread 1/3 of the filling on the cake, spreading to within about ½" of the edge. 

18. Top with a chocolate layer. Spread with 1/3 of the filling. 

19. Top with the second vanilla layer. Spread with the remaining filling. 

20. Top with the second chocolate layer. 

Directions (General Intermediate)

21. Anchor the layers together with cake testers, broom straws, or bamboo skewers, so they remain perfectly centered as the filling cools. 

22. It’s best to let the filling set for an hour or so before making the icing and finishing the cake.

Directions (Icing)

23. Combine the chocolate and cream in a microwave-safe bowl.

24. Heat until the cream is very hot, and the chocolate very soft.
25. Stir to melt the chocolate completely, reheating very briefly if necessary. 

26. Pour and spread the icing over the top of the cake, letting it drip over the edges and down the sides. 

27. Once it’s done dripping, smooth the sides with a spatula. 

28. Add sugar decorations while the icing is still warm, if desired. 

29. Allow the cake to rest, covered with a cake cover (or a big turned-over bowl) till the chocolate is set; overnight is good, though several hours are sufficient.