Chocolate German Buttercream (and the cupcakes we ate it on)
I wish I had a photograph for you of the buttercream-topped cupcake, complete with sprinkles and a sugar rose, that was assembled for my Smallest Roommate's birthday. But at least I have the recipes!
I must admit, I'm writing this entry to sing the praises of the german buttercream. I first saw it in Cook's Illustrated's Dacquoise recipe, and when I went looking I found
BraveTart's excellent weights-based recipe. She says it tastes like ice cream, and she's right -- the chocolate buttercream tasted surprisingly like excellent chocolate ice cream, without the chill.
The recipe is composed of a pudding plus butter and sugar, and since the flavor goes into the pudding it's very easy to vary flavors. Here's the volume-based recipe I came up with (since I lack a kitchen scale)
Pudding:
1/4 cup dutched cocoa
3 tbsp cornstarch (I made the pudding thick for stability; feel free to use less)
1/4 tsp salt
1 cup whole milk
1/2 cup brown sugar
2 egg yolks
2 tsp vanilla (modify to taste)
1 stick aka 1/2 cup butter, sliced or cubed
4 oz by weight dark chocolate, chopped finely (sorry, but then they do sell it by weight)
1/2 tsp espresso powder, optional
Place the cocoa, cornstarch, and salt in a medium saucepan, and whisk to combine. Slowly whisk in the milk and then the sugar and egg yolks. Whisking continuously, bring to a bubbling boil over medium-high heat and cook for about 30 seconds, then remove from the heat. Add the remaining ingredients, stir well, and leave to sit for five minutes, then whisk until smooth.
As BraveTart says, this next step is very important: COOL THE PUDDING COMPLETELY. I did this by placing it in a small metal bowl in the freezer for an hour, then moving it to the fridge until I was ready to make the frosting.
To make the frosting:
1 stick soft butter
1-2 cups powdered sugar
Additional vanilla, espresso powder, or salt if desired
Place the pudding in a stand mixer or a bowl that accomodates a hand mixer, and beat at medium speed till creamy. Reduce the speed to low and add the butter and sugar in alternating installments until the butter is all incorporated and the frosting is as sweet as you like. If necessary, adjust the flavors, then beat at medium-high for about a minute till smooth and fluffy. Chill if desired or frost right away.
It's not the stiffest frosting, but all I wanted was something tasty to cover the cupcakes with, and it was also easy and delicious (without the butter-overload flavor of some frostings).
We put it on these, based on Alton Brown's Devil's Food Cake recipe:
1/2 cup boiling water
4 ounces Dutch process cocoa
1&1/2 cups dark brown sugar
2 cups all-purpose flour
2 tbsp cornstarch (or use half AP and half cake flour plus 1/4 cup cake flour, and omit the cornstarch)
1 teaspoon baking soda
1/2 teaspoon kosher salt
1 cup vegetable oil
1/2 cup buttermilk
2 large whole eggs, room temperature
2 large egg yolks, room temperature
Directions
Set a rack in the middle of the oven and preheat to 325 degrees F.
Line a muffin tin with paper muffin cups. Set aside.
Whisk the boiling water and cocoa powder together in a small bowl and set aside.
Combine the sugar, flour, baking soda, and salt in the bowl of a stand mixer fitted with the paddle attachment. Whisk the oil, buttermilk, eggs, and egg yolks in a large pourable vessel. Add the cocoa and water mixture to the oil mixture and slowly whisk to combine.
With the mixer on low speed, add the liquid mixture to the dry mixture over 30 seconds. Continue to beat on low speed for another 30 seconds. Stop and scrape down the sides of the bowl. Continue to beat on low speed until the batter is smooth, 10 to 15 seconds.
Pour the batter into the prepared pan and bake until the cake springs back when pressed and reaches an internal temperature of 205 degrees F, 20 to 25 minutes.
Cool in the pan on a rack for 20 minutes, and then remove from the pan and cool completely before frosting, about 1 hour.
The yield will depend on your muffin cup sizes -- this gave 6 large size and 12 regular size cupcakes.