Daring Bakers, May 2008 - Opéra

This months Daring Bakers chalange is Opéra cake, and it's dedicated to Barbara from winosandfoodies.com. This time, I decided to keep it simple, and not alter the recipe in any way.

This recipe is based on Opéra Cake recipes in Dorie Greenspan’s Paris Sweets and Tish Boyle and Timothy Moriarty’s Chocolate Passion.

For the Joconde:

6 large egg whites, at room temperature
30 g granulated sugar
225 g ground blanched almonds (You can make it at home by grinding almonds in the food processor with a tablespoon or two of the flour that you would use in the cake. The reason you need the flour is to prevent the almonds from turning oily or pasty in the processor. You will need about 2 cups of blanched almonds to create enough almond meal for this cake.)
2 cups icing sugar, sifted
6 large eggs
70 g all-purpose flour
45 g unsalted butter, melted and cooled

Divide the oven into thirds by positioning a rack in the upper third of the oven and the lower third of the oven. Preheat the oven to 220°C. Line two 31x39 cm jelly-roll pans with parchment paper and brush with melted butter.

In the bowl of a stand mixer fitted with the whisk attachment (or using a handheld mixer), beat the egg whites until they form soft peaks. Add the granulated sugar and beat until the peaks are stiff and glossy. If you do not have another mixer bowl, gently scrape the meringue into another bowl and set aside. If you only have one bowl, wash it after removing the egg whites or if you have a second bowl, use that one. Attach the paddle attachment to the stand mixer (or using a handheld mixer again) and beat the almonds, icing sugar and eggs on medium speed until light and voluminous, about 3 minutes. Add the flour and beat on low speed until the flour is just combined (be very careful not to overmix here!!!).

Using a rubber spatula, gently fold the meringue into the almond mixture and then fold in the melted butter. Divide the batter between the pans and spread it evenly to cover the entire surface of each pan.

Bake the cake layers until they are lightly browned and just springy to the touch. This could take anywhere from 5 to 9 minutes depending on your oven, mine was done after 6 minutes. Place one jelly-roll pan in the middle of the oven and the second jelly-roll pan in the bottom third of the oven.

Put the pans on a heatproof counter and run a sharp knife along the edges of the cake to loosen it from the pan. Cover each with a sheet of parchment or wax paper, turn the pans over, and unmold. Carefully peel away the parchment, then turn the parchment over and use it to cover the cakes. Let the cakes cool to room temperature.

For the syrup:

125 g water
65 g granulated sugar
1 bag vanilla sugar

Stir all the syrup ingredients together in the saucepan and bring to a boil. Remove from the heat and let cool to room temperature.

For the buttercream:

100 g granulated sugar
60 g water
1 large egg
1 large egg yolk
200 g unsalted butter, at room temperature
50 g melted white chocolate

Combine the sugar and water in a small saucepan and warm over medium heat just until the sugar dissolves. Continue to cook, without stirring, until the syrup reaches 107°C on a candy or instant-read thermometer. Once it reaches that temperature, remove the syrup from the heat.

While the syrup is heating, begin whisking the egg and egg yolk at high speed in the bowl of your mixer using the whisk attachment. Whisk them until they are pale and foamy.

When the sugar syrup reaches the correct temperature and you remove it from the heat, reduce the mixer speed to low speed and begin slowly (very slowly) pouring the syrup down the side of the bowl being very careful not to splatter the syrup into the path of the whisk attachment. Some of the syrup will spin onto the sides of the bowl but don’t worry about this and don’t try to stir it into the mixture as it will harden! Raise the speed to medium-high and continue beating until the eggs are thick and satiny and the mixture is cool to the touch (about 5 minutes or so).

While the egg mixture is beating, place the softened butter in a bowl and mash it with a spatula until you have a soft creamy mass. With the mixer on medium speed, begin adding in two-tablespoon chunks. When all the butter has been incorporated, raise the mixer speed to high and beat until the buttercream is thick and shiny. At this point add in melted white chocolate and beat for an additional minute or so.

Refrigerate the buttercream, stirring it often, until it’s set enough (firm enough) to spread when topped with a layer of cake (about 20 minutes).


For the white chocolate ganache/mousse:

210 g white chocolate
1 cup plus 3 Tbsp heavy cream (35% cream)

Melt the white chocolate and the 3 tbsp. of heavy cream in a small saucepan. Stir to ensure that it’s smooth and that the chocolate is melted. Set aside to cool completely. In the bowl of a stand mixer, whip the remaining 1 cup of heavy cream until soft peaks form. Gently fold the whipped cream into the cooled chocolate to form a mousse.

For the glaze:

420 g white chocolate, coarsely chopped
1/2 cup heavy cream (35% cream)

Melt the white chocolate with the heavy cream. Whisk the mixture gently until smooth. Let cool for 10 minutes and then pour over the chilled cake. Using a long metal cake spatula, smooth out into an even layer. Place the cake into the refrigerator for 30 minutes to set.

Assembling the Opéra Cake:

Line a baking sheet with parchment or wax paper.

Working with one sheet of cake at a time, cut and trim each sheet so that you have two pieces (from each cake so you’ll have four pieces in total): one 25 cm square and one 25 x 12,5 cm rectangle.

Place one square of cake on the baking sheet and moisten it gently with the flavoured syrup. Spread about three-quarters of the buttercream over this layer. Top with the two rectangular pieces of cake, placing them side by side to form a square. Moisten these pieces with the flavoured syrup. Spread the remaining buttercream on the cake and then top with the third square of joconde. Use the remaining syrup to wet the joconde and then refrigerate until very firm (at least half an hour).

Prepare the ganache/mousse (if you haven’t already) and then spread it on the top of the last layer of the joconde. Refrigerate for at least two to three hours to give the ganache/mousse the opportunity to firm up.

Make the glaze and after it has cooled, pour/spread it over the top of the chilled cake. Refrigerate the cake again to set the glaze.

Serve the cake slightly chilled. This recipe will yield approximately 20 servings.

For more Opéras, visit this month's hosts Ivonne and Lis, their co-hosts Fran and Shea and the rest of the DB crew.