Black Forest Cake part 1: Chocolate Génoise

Debby’s father’s birthday is coming up and one of her sisters is visiting. We decided to be overly ambitious and make a chocolate cake. Not content with just making a cake (I’m usually more of a pie person), I decided that Joe Pastry’s Black Forest Cake looked good. It starts with his Chocolate Génoise

2 ounces (4 tablespoons) unsalted butter
3.5 ounces (3/4 cup) cake flour
0.75 ounces (1/4 cup) Dutch-process cocoa
1/2 teaspoon salt
6 eggs, room temperature
5.25 ounces (3/4 cup) sugar
1 teaspoon vanilla extract

The basic idea is to make an egg foam and fold in the dry ingredients. Note that there is no other leavening! The first problem is figuring out how to do the eggs. There are two issues from using Joe’s recipe.

  • I don’t have a stand mixer, which is not a big deal. But I need to figure out the appropriate volume container to use. It seems like typical stand mixer bowls are 4.5-5 quarts. On the other hand, the whole thing is going to fit into a 9″ springform pan. First discovery: the springform pan is not watertight enough to empirically measure its volume. So let’s calculate: 2.8 in h x 3.14 x 4.5 in ^2 =  178 in^3 = 12.3 cups, which is sort of consistent with this site, which gives 12 cups as the volume for 2 regular 9 in cake pans. But I assume we’re not going to fill the pan to the rim.
  • The related problem is how to heat the mixture without cooking it. This depends on what the container will fit in! Joe puts his mixing bowl over a pan of boiling water to heat the eggs, and monitors the temperature while whipping.

I’ve been looking for an excuse to buy a stick blender, so I used this as a chance to get the Cuisinart Smart Stick with a whisk attachment.

Note to self: melting butter in the microwave is not a good idea.

My solution to the egg beating was to use my Anova Precision Cooker to  hold a water bath at 115°F. The Anova is nice for this compared to my older Nomiku because it can work in a shallower water bath.

The pic shows the setup about halfway through the beating of the egg-sugar mixture. It ended up increasing in volume another inch or so… if I do this again I need a larger bowl.

I mixed about a cup of the egg foam with the melted butter and then transferred the whole thing to a larger bowl. I gently whisked in the flour and cocoa, leaving a few irregularities.

After pouring the batter into the pan (another new purchase!), I noticed that I had not put parchment on the sides. Hmm… too late to fix, and it’s a nonstick pan. Baked for 30 min at 375. Toothpick came out clean. Done at about 5PM on Sunday afternoon.

I did the double flip with parchment onto the cooling rack as described in Joe’s post, but I’m not sure why I needed to get the lower parchment out… his photo looks like the cake is back onto the lower panel of the springform pan.

Comparing my cake to his pictures, mine looks a bit more like the bottom of a cone. The sides came away from the walls of the pan, making the cake a bit narrower at the top than at the bottom. I wonder if this is related to the lack of wall parchment.

But I’m happy with how it came out – i.e. not collapsed – and it smells amazing.