Saturday, July 2, 2011

Chocolate cake: A scientific method

I am in France right now! But before I blog about that, I will tell you about my attempts to make a near perfect chocolate cake.

A few weeks ago, a friend asked me to bake a cake for another friend's surprise birthday/goodbye party. A commission of sorts! How honoring and surprising! I was told that the recipient like chocolate cake, and the theme of the party was Pink Lemonade (pink and yellow), so I was a bit stumped on how to combine them. I personally am not a fan of lemon and chocolate (I am actually not a fan of any lemon desserts), so I figured I could just add pink and yellow food coloring in a couple places. Unfortunately, chocolate cake is not very easy to color... I considered red velvet, but the one time I tried to make red velvet cupcakes, they did not turn out well at all. And by at all, I mean at all. As I only had 1.5 weeks to prepare, I wanted to stay on the safe side.

But how to add color to a chocolate cake? White chocolate frosting.

I began with the base of the cake. I wanted the base to be good, not just sweet and fluffy, so I gathered a couple recipes. I decided to try two of them: a relatively simple recipe from Scharffen-Berger (that I had made before here) and a more complicated recipe from Cook's Illustrated (which was surprisingly available on their website while I was making the cake, but is now only available to subscribers here). I made half of each recipe to get one layer of each.

For the frosting I turned to one of my favorite cookbooks: I Want Chocolate! by Trish Deseine. I made half of her recipe for Easy Chocolate Ganache, substituting white chocolate for dark. If I remember correctly, it used about 3/4 cup for 8oz of chocolate. This turned out to be a bit to liquid for my purposes, so I had to almost freeze my ganache for it to be thick enough. I often find frosting to be too rich, so I wanted to test two different ganaches, a heavier one (just cream and chocolate) and a lighter one (cream, chocolate and whipped cream). So I made both and colored the heavier one yellow and the lighter one pink.

Then I assembled my test cake. On the bottom I put my layer of simple cake,

 then I spread some heavier frosting,
 put the complicated cake,
and spread the lighter frosting. I did not have enough lighter frosting to cover the entire cake, so it ended up looking pretty ugly. That's why I had a test cake!

Then I had my parents test the cake. I did not tell them which layer corresponded to which cake (because that would have biased the data. I should have made two half cakes, one with the layers in the opposite order, for less bias, but I was worried that would not be stable).

Results: First, the top layer is lighter colored. However, it was also found to be more strongly chocolatey, as well as more tender and lighter than the bottom layer. The bottom layer was not found to have any redeeming qualities in comparison with the top layer. Fortunately for me, the choice was easy. Unfortunately, the chosen cake was the more complicated recipe.

As for the frosting, I decided that I liked having the two types, but that I should switch their positions.

Making the final cake:
I had originally planed to have a second practice cake, but I was out of time, so I went directly to the final cake. I made the full Cook's Illustrated recipe for the base and made ganache with 12oz of white chocolate and 3/4 cup of cream. I put the lighter frosting in between the cake layers and tried to spread the thicker frosting on top. However, the thicker ganache was now too thick to spread easily, and cake crumbs got mixed into the frosting, ruining the smooth finish:
To solve this, I made another batch of ganache using 8oz of white chocolate and spread it on top of the previous layer of frosting. For decoration, I had made letters and shapes with colored melted white chocolate:

The cake was a success, my friends really liked it!

A note: for all of this, I used white chocolate bars. I strongly recommend NOT using so called "White Chips" as these contain absolutely no cocoa butter and have a very different texture when melted.

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