Monday, May 17, 2010

Lemon-White Chocolate Truffle Cake

This weekend was a bit of a whirlwind. My not-so-little brother got married! He and his beloved had many festivities that I participated in, all lovely. But for the bridal shower I got to bake.

The morning of I woke up at 4:30 am without an alarm clock and without a hardly a sigh I was up and tip-toeing my way to the kitchen. I made two batches of cinnamon rolls, two quiches, and this cake before 10:30 that morning. I am a little surprised that I was so thrilled about it, and I am floored that I was able to finish.

I have catered events like this before. In Vancouver my partner and I prepared a bridal shower tea with cookies and little sandwiches, elderberry flower cordial and quiche. But I guess I had forgotten what I loved about those gigs: the short-term deadline when you don't do much ahead of time. You buy the food. You prepare it. People eat it. You get paid. You go home. If it was great it was great. If it was stressful or a flop at least it only lasted a day.

This time I only made those few things and did not cater the whole shower. And I didn't do it all the morning of. I baked the cake and made the buttercream the day before, then assembled it that morning. If I had to do it again I would make the cinnamon roll dough the night before, let it rise overnight in the fridge, and bake the cake the same day. The cake is much better fresh, where the delicate center is moist and the outer edges still  tend toward a proper crust. When it sits the moisture redistributes, making the center less moist and the exterior soft.


I have to sheepishly confess that this was my first time making Rose's buttercream with cooked sugar. I usually make her Neoclassic Buttercream, which calls for corn syrup instead of sugar, making the boiling process more predictable: when it comes to a full boil, you know it's at the soft ball stage--without a doubt and without a concern for crystals. But woe of woes--it uses corn syrup. Corn syrup. I don't do corn syrup. It is one of those little obnoxious things I do in lieu of healthy eating and GMO food banning. When I bought some at the store a while back for another cake and came home with it under my sweater, or when I wanted to hide it under my sweater, I thought maybe I should bite the bullet and try to cook sugar.

So with excessive encouragement from my sister (because now she has cooked sugar) I prepared to make the Classic Buttercream recipe. I borrowed a candy thermometer. I breathed deeply. I cooked sugar to the soft ball stage.

And you know what? It was not hard at all. You just sit there and stare at the little red line. It rises slowly. And then when it hits the mark, you turn off the burner and pour out the burn-off-your-flesh-hot sugar.
This go around on the buttercream took me even less time than it has in the past. And the results were identical, just as Rose says.

The cake I made has a slight tang to it that I did not expect, which echoes the lemon buttercream. And the fragrance of the vanilla bean in the ganache makes the white chocolate sing a bit more than if otherwise alone.

When iced and finished (I didn't get a picture of it--so, so sad) the cake is elegant and poised, with a smooth surface from the ganache enrobing and the lovely little flecks of vanilla bean. I decorated with lemon curls and slices, but I am such a fan of edible decorations, I would pipe a buttercream design on it maybe.
Be very aware of temperature, as I thought the buttercream and ganache were a little too warm and soft. I like to take the cake from the refrigerator and sit out to soften for half hour before serving. 

Lemon-White Chocolate Truffle Cake

Whatever order you make the cake and its components, I suggest making the ganache just prior to pouring it. It takes about ten minutes to make and is at the perfect temperature and consistency to pour if you do this.


For the Buttercream: (adapted from The Cake Bible, by Rose Levy Beranbaum):

Ms. B says that 99% of the time any issue with the buttercream (assuming you made it correctly), such as curdling or separating or general chunkiness, is because it is not at the proper temperature, so make sure it is perfectly room temperature (or slightly cooler) before you try and work with it. If it is lumpy try heating the bowl just slightly, then beat it thoroughly. If it is a hot day beware of melting--of both you and the icing.

6 large egg yolks
1 cup sugar
1/4 cup water and 1/4 cup lemon juice
2 cups butter
1/4 teaspoon lemon extract
extra 2-4 tablespoons lemon juice or lemoncello (optional)

Have ready a buttered pyrex liquid measure and either a wooden spoon or a heatproof silicone spaturla ready and near the stove.

In a medium bowl beat the egg yolks until thick like honey and pale like sunshine. If you have a hand free, that is, when you have a hand free (either by nature of being done beating or if you are utilizing a stand mixer), heat the sugar, lemon juice, and water in a small saucepan over medium-high heat stirring constantly until the sugar dissolves and the syrup comes to a boil. Stop stirring and boil to the soft-ball stage (238 degrees Fahrenheit). Immediately transfer the syrup to the glass measure to stop the cooking, scraping out the saucepan.

If using a hand-held mixer, beat the syrup into the yolks a little at a time at first, avoiding the beaters, and then in a steady stream when you have tempered the eggs a bit. If using a stand mixer, take a deep breath. While the mixer is off, pour a bit of the syrup into the bowl, again, avoiding the beaters. In nearly the same motion turn on the mixer to high and beat for one slow-ish breath, or about five seconds. Stop the mixer and repeat with a greater amount of the syrup, beating again for a slow-ish breath. Do this off-pour-on-beat until the syrup is gone. Be sure to scrape down the sides after the last addition and before the beating. Leave to beat on high until the bowl is room temperature.

When the egg syrup is ready, beat in the butter, nub by nub until all the butter had been added and the mixture is thick, glossy, and smooth. This takes a few minutes. Add the lemon extract and the extra juice, if using. Ice cake or Store in an airtight container until needed. I vasselate between opinions: make ahead and not have to worry about buttercream at the last minute but be stuck with getting it to the right temperature, or making as soon as you will need it, no cooling and no gentle heating, but no comfort in a buttercream that is made ahead? Note the pros and cons and good luck to you.

The buttercream stores well for a week (or a little more) refrigerated or in the freezer for much longer. On a cool day it can sit out half the day at room temperature, but if it is at all hot, don't take the melting risk. It is much easier to heat buttercream to the right temperature than to cool it off. Enjoy!


For the White Chocolate Cake: (also adapted from The Cake Bible):

6 ounces white chocolate
6 large egg yolks
1 cup milk
1 1/2 teaspoons vanilla
3 cups sifted cake flour
1 cup + 3 tablespoons sugar
1 tablespoon + 1 1/2 baking powder
3/4 teaspoon salt
9 tablespoons unsalted butter

Preheat oven to 350 degrees.

In a double boiler melt the chocolate over simmering water, stirring constantly until the white chocolate is half melted. Take off the heat and stir until smooth. Let cool.

In a medium, bowl lightly combine the yolks, 1/4 cup milk, and vanilla.

In a large mixing bowl combine the dry ingredients and mix on low speed for 30 seconds to blend. Add the butter and remaining 3/4 cup milk. Mix on low speed until dry ingredients are moistened. Increase to medium, speed and beat for 1 1/2 minutes more to aerate and develop the cake's structure. Scrape down the sides. Gradually add the egg mixture in 3 batches, beating for 20 seconds after each addition to incorporate the ingredients and strengthen the structure. Scrape down sides. Add the melted chocolate and beat to incorporate.

Scrape the batter into the prepared pans and smooth the surface with a spatula (making sure it really is even because it becomes wonky easily). Bake 25-35 minutes or until a tester inserted near the center comes out clean and the cake springs back when pressed lightly in the center. The cakes should start to shrink from the sides of the pans only after removal from the oven. Let the cakes cool in the pans on racks for 10 minutes. Loosen the sides with a knife and invert onto greased wire racks. Reinvert so that tops are up, and cool completely before wrapping airtight.

For the Ganache: (Inspired by Cocoa Nymph's white chocolate and vanilla bean truffle The Amy:

equal parts real white chocolate and heavy whipping cream
1 vanilla bean, split
1/2 cup butter, mostly softened

Heat cream and scrapings from the vanilla bean on medium-high heat until bubbles for around the sides. Let sit until half-cooled. It should be still warm but not hot when you add it to the chocolate

Place chocolate in a food processor, and while it is running, add cream mix in a steady stream. Process until machine becomes fairly quiet (there should not be anymore white chocolate chunks in it). Add butter a little at a time with processor on.

Let cool a little more if it is still fairly runny. Feel the temperature. It should be tepid when poured.

Assembly:

Layer buttercream between the two cake layers. Ice the cake with the leftovers. Refrigerate for about an hour. Pour prepared ganache over the cake (on a rack on a cookie sheet with sides). You can push the ganache a little to aid in its flow over the sides. Try and make it even. Refrigerate until set. Pour one more time over the cake and let drip down sides slightly. don't be tempted this time to touch the ganache. The cooler it becomes, the more you should not 'help' it. Delicately transfer cake to a cake plate or board and serve. Enjoy!

3 comments:

  1. Amanda,
    All of the goodies you baked for the shower were magnificent!!! My Mum is still going on about your delicious lemon cake :o)
    I love love love your cinnamon rolls!!
    Thank you for baking, everything was perfect.
    Chrissie

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  2. I enjoyed this cake at Michelle's wedding shower, it was absolutely delicious! I am a big fan of lemon cake (and deserts) and this was by far the best I've ever had. It was moist, sweet and tangy. The chocolate ganache was heavenly, so good in fact I had to have a second piece, completely wrecking my diet, but worth every bite. I've loved reading your blog and look forward to trying some of the recipes. Thank you for sharing this recipe, your wisdom, tips and thoughts.
    -Melissa (Danielle's friend)

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  3. Thanks Melissa! Lemon just does something for the psyche (and palate) doesn't it? Bright, light-tasting even when rich, and so nice with creaminess. I am giving myself a craving...

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