There’s little more in life that I enjoy more than planning a PARTY, for lord’s sake. Fortunately, the best aspect of being known to know how to cook is getting tapped early for party plans. Not to say that my winning charms aren’t sufficient on their own mind you, but let’s be real here, the cake helps. It’s been a while, though, since I’ve had the chance to make a birthday cake so I was particularly pumped to receive my marching orders for a cake as chocolate as possible for a good friend’s 1/3 centennial celebration.
Given that I didn’t really have much more than that to go on, though, it took a bit of thinking to get my plan of action together. Since I wasn’t sure how many people would be there, or how many of them would actually EAT CAKE (queens and their carb counts, I swear…), I elected to do a sheet cake. They’re easier to cut and portion than a round, feed more people, and supply a broader canvas on which to write… “Happy Birthday Whomever” is a lot of letters, people!
The Cook’s Illustrated German Chocolate Cake was what I went with. It has a nice mellow chocolatey flavor and tight, moist, sturdy crumb that would be critical as I was planning to split and fill it with a bittersweet ganache before frosting it with a billowy chocolate egg white buttercream. The ganache, in the Rose method, was as spectacular as it is easy. Dump, blitz, pour, and wait. That’s it. If only everything was so simple. Even using a mid-range Ghiradelli 60% (which was the only 60% I could find…hmph), the resulting ganache was amazing, with a smoky, dusky depth of flavor that provided a nice counterpoint to the mellow cake and sweet buttercream.
While I’ve been wanting to try out a mousseline buttercream, and have even consulted the experts in that regard, I went with an easier, quicker chocolate egg white buttercream in this instance. It was for a weeknight party and I didn’t quite have the wherewithall to race around with molten sugar the evening of the event. Fortunately, the buttercream was a lovely one that tied everything together well. Using just ganache or buttercream as both frosting and filling would have been too much of either; a little of both, however, was perfect.
I would recommend spreading the preparations out over the course of a few days. It’s a little less crazy than trying to do it all at once (though it’s possible…), and the final assembly will go much better if the cake is chilled and the ganache is at cool room temperature. I baked the cake two days before, did the ganache one day before, and made the frosting and assembled the cake the day of.
Triple Chocolate Birthday Cake
Make the Cake:
German Chocolate Sheet Cake
4 oz semi- or bittersweet chocolate, chopped fine
1/4 c Dutch-processed cocoa, sifted
1/2 c boiling water
2 c unbleached all-purpose flour (10 oz)
3/4 tsp baking soda
12 tbs unsalted butter, softened
1 c granulated sugar (7 oz)
2/3 c packed light brown sugar
3/4 tsp table salt
4 large eggs, room temperature
1 tsp vanilla extract
3/4 c sour cream, room temperature
Adjust oven rack to lower-middle position; heat oven to 350 degrees F. Combine chocolate and (sifted!) cocoa in a small bowl; pour boiling water and let stand to melt chocolate, about 2 min. Whisk until smooth; set aside until cooled to room temperature.
Spray a 13 x 9 inch baking pan with nonstick cooking spray (or butter). Line bottom of pan with parchment paper and spray (or butter). Dust pan with flour, and knock out excess. Set aside. Sift flour and baking soda into a medium bowl. Set aside.
In bowl of a stand mixer, beat butter, sugars, and salt at medium-low speed until sugar is moistened, about 30 seconds. Increase speed to medium-high and beat until mixture is light and fluffy, about 4 min, scraping down the bowl halfway through. With mixer running at medium speed, add the eggs one at a time, beating well after each addition and scraping down the bowl halfway through. Beat in the vanilla. Increase speed to medium-high and beat until light and fluffy, about 45 seconds. With mixer running at low speed, add chocolate, then increase to medium and beat until combined, about 30 seconds, scraping down the bowl once. (Batter may appear broken.) With mixer running at low speed, add dry ingredients in 3 additions, alternating with the sour cream (in 2 additions), beginning and ending with dry ingredients and beating in each addition until barely combined. After final flour addition, beat on low until just combined, then stir the batter by hand with a rubber spatula, scraping bottom and sides of bowl to ensure that batter is homogenous (batter will be thick). Pour into prepared pan and level with an offset spatula.
Bake cake until toothpick (or cake tester) comes out clean (30-35 min; or a little longer… I’ve pushed it to 40 min). Cool the cake in the pan on a rack for 10 min, then invert cake onto a greased wire rack. Peel off and discard parchment from bottom of cake. Reinvert cake on another rack and cool to room temperature before wrapping carefully in plastic wrap and refrigerating till assembly.
Make the Ganache:
RLB’s YouTube Ganache
See it here
10 oz bittersweet chocolate
11 0z cream
In a small saucepan, scald cream–bring it almost to the boil. Little bubbles should be forming around the edges. Meanwhile, in the bowl of a food processor, chop chocolate till quite fine–powdery, but not melty. With the food processor running, add hot cream via the feed tube and process till combined, about 15 seconds. Scrape it all down and process just a second more. Pour into a bowl and let cool to room temperature before covering with plastic wrap. If using within 24 hours, it can stand unrefrigerated. If waiting longer, refrigerate once cooled and covered.
Make the Buttercream:
Classic Egg White Chocolate Buttercream
Rose Levy Beranbaum, The Cake Bible
10 oz bittersweet chocolate (60%)
1 lb unsalted butter, slightly softened
4 large egg whites, room temperature
1 c sugar
(These are not the RLB directions; this is how I do fudge it. )Chop the chocolate finely and melt in the microwave using 15 second bursts and stirring every time. Remove from microwave before fully melted and stir, allowing residual heat to finish the job. Set chocolate aside to cool to room temperature.
In the bowl of a stand mixer fitted with the paddle attachment, beat the (not really very softened at all) butter till light and fluffy, about 4 minutes. Butter should be cool to touch, but soft and light. Remove bowl and paddle attachment and set both aside.
In another, scrupulously clean mixing bowl, beat the egg whites with the whisk attachment until soft peaks form. With the mixer running, gradually add the sugar and beat until stiff peaks form when the beater is raised slowly. Swap in the paddle attachment and beat in the butter 1 tbs at a time at medium speed. If mixture starts to curdle, increase speed a little and beat until smooth before adding more butter. Once butter is all incorporated, add melted and cooled chocolate all at once and beat until smoothly incorporated and uniform in color, scraping down the bowl as necessary.
Assemble the Cake:
Remove cake from refrigerator and place on a cutting board. Using a long serrated knife, trim edges flush and even out top of cake. Split the cake in half horizontally. There are several ways to do this; freehand, marking the desired split line all the way around the cake with toothpicks and then cutting, or using a length of floss and spacers that will keep the floss at the cake’s midpoint. This latter way is by far the best–particularly when splitting a cake this large–but does necessitate finding to items half as high as your cake and you can use to ensure your floss cuts evenly. It’s worth the rummaging, trust me.
Carefully, using broad spatulas or the backs of your hands, transfer one half of the cake to your serving platter. Brush off any crumbs. Spread a generous 2/3 of the ganache over the cake in a smooth ~1/4″ layer, reserving the rest. Put the ganache-topped cake in the refrigerator while you fill a pastry bag fitted with a small star tip with the remaining ganache. Set filled pastry bag aside. Retrieve the cake from the refrigerator and carefully place the remaining cake layer on top. Smooth the sides of the cake with any ganache sticking out and put cake back in the refrigerator for 10 minutes. Take the cake out and spread a generous 1/2 of the frosting over the top of the cake in a ~1/4″ layer. Frost the sides with a similar thickness. You will have some frosting leftover. Smooth out the top and sides and refrigerate for 10-15 min.
Meanwhile, massage the pastry bag of ganache a little to warm it up a bit. Take the cake from the refrigerator and pipe a star border around the bottom and top edges of the cake. Replace the star tip with a small plain writing tip (#3 or #4) and write your “Happy Whatever Whomever”. (Do the borders first THEN the writing, the former is easiest when the ganache is still firm, the latter is easiest when the ganache is very soft.) Put BACK in the refrigerator to reset the frosting and ganache and then drag you and your cake off to the party. PARTY, YAY!