This cake does well to bring the chocolate frosting into the spotlight. It is a soft and creamy delight. The sponge is very light and fluffy which balances out the rather heavy chocolate frosting perfectly. It's an easy crowd-pleaser. Smitten Kitchen to the rescue again, when I was looking for an easy cake to pull out. This is an adaptation of her Best Birthday Cake and the frosting is an adaptation of The Dessert Bible's Chocolate Sour Cream Frosting. 

Ingredients:

Cake: 

480 grams cake flour

10 grams baking powder

1-1/2 tsp baking soda

1 tsp salt

225 grams (2 sticks) unsalted butter, softened

350 grams sugar

3 tsp vanilla extract

4 large eggs, at room temperature

475 ml (2 cups) buttermilk

Chocolate Sour Cream Frosting:

(Yield: 5 cups)

Directions:

1. Grease and line with parchment your cake pans. Then, grease the parchment paper. 

2. In a bowl, sift flour, baking powder, baking soda, and salt. 

3. Using a stand mixer, beat butter and sugar at medium setting. 

4. When the mixture is pale and fluffy, add in the vanilla.

5. Beat in the eggs one at a time, scraping the bowl down after each egg. 

6. Decrease the speed and add in the buttermilk until it just starts to come together. The mixture may look curdled, this is perfectly fine. 

7. Add the flour mixture one third at a time, mixing until just incorporated. 

8. Pour the batter in the cake pan, tapping the cake pan on your counter to get rid of air inside the mixture. 

9. Bake for about 35 minutes in an oven preheated to 350ºC until golden and a cake tester comes out clean when inserted into the centre of the cake. 

10. Let the cakes cool on a cooling rack for 10 minutes.

11. Run a knife around the edge of the cake pan. 

12. Remove the cake from the cake pan too cool completely.

13. In a bowl, microwave the chocolate and espresso powder together in 30-second bursts, making sure to stir after every 30 seconds. 

14. Once the chocolate has melted, set aside to let cool to room temperature. 

15. In the meantime, whisk the sour cream, 1/4 cup corn syrup, and vanilla.

16. When they have combined, stir the chocolate in quickly until combined completely.

17. Taste. If the frosting is not sweet enough, add in a little bit more corn syrup at a time until you are satisfied. 

18. Chill the frosting in the refrigerator for about 20 minutes or when it can be easily spread onto cake. 

19. Decorate cake as desired.