Wednesday, May 28, 2008

White Chocolate Raspberry Opéra Cake: A Daring Bakers Challenge

When Lis, Ivonne, Fran and Shea announced this month's Daring Baker Challenge -- an opera cake sans the traditional coffee and dark chocolate flavors -- I was apprehensive.

What flavors should I use to make this my own?

How many steps in this recipe?

How many ingredients? How much will they cost?

How much time will I be in the kitchen?

But by god, it's all worth it -- the result is fantastic. From the cake's delicate crumb, to the richness of the chocolate mousse, to the buttercream bursting with freshness, this is a divine dessert. On top of all that, the opera cake is so elegant and beautiful, it's almost too beautiful to cut into. Almost.

If you look at the recipe below, chances are you'll be intimidated by it. It's very long and there are lots of elements to it. But let me let you in on a secret:

It's really not as difficult as it first appears.

Yes, there are lots of steps to make the five separate elements -- joconde cake, buttercream, syrup, mousse, and glaze -- but everything but the glaze can be done ahead of time and refrigerated, allowing you to make this in your own time.

So thank you Lis, Ivonne, Fran and Shea for a terrific challenge! As usual, the DBers have pushed me to keep learning and exploring in the kitchen. Check out the Daring Bakers Blogroll for hundreds of variations on the Opera Cake and stop by the Daring Bakers forum and say "hi!"

White Chocolate Raspberry Opéra Cake

If you don't like white chocolate, give Green & Black's white chocolate a try. It's not like other white chocolates; it's nicely flavored with vanilla bean, almost like the most premium vanilla ice cream transformed into a white chocolate bar. I highly recommend it, and used it throughout this recipe.

Elements of this Opéra Cake:

Joconde: The base of an Opéra Cake is a thin sponge cake that is made traditionally with almond meal (finely ground blanched almonds).

Syrup: The joconde is flavoured with a sugar syrup.

Buttercream: The first two layers of the joconde are covered in a rich buttercream. This particular buttercream is made with a syrup, eggs and butter.

Mousse: the final layer of the joconde is covered in a white chocolate mousse.

Glaze: The final step to an Opéra Cake is the glaze that gives the cake a very finished and elegant appearance.

(Note: can be made up to 1 day in advance and kept wrapped at room temperate)

What you’ll need:
•2 12½ x 15½-inch (31 x 39-cm) jelly-roll pans (Note: You can use different-sized jelly-roll pans like 10 x 15-inches.)
•a few tablespoons of melted butter (in addition to what’s called for in the ingredients’ list) and a brush (to grease the pans)
•parchment paper
•a whisk and a paddle attachment for a stand mixer or for a handheld mixer
•two mixing bowls (you can make do with one but it’s preferable to have two)

6 large egg whites, at room temperature
2 Tbsp. granulated sugar
2 cups ground blanched almonds
2 cups confectioners' sugar, sifted
6 large eggs
½ cup all-purpose flour
3 Tbsp. unsalted butter, melted and cooled

1. Divide the oven into thirds by positioning a rack in the upper third of the oven and the lower third of the oven.

2.Preheat the oven to 425-degrees F.

3.Line two jelly-roll pans with parchment paper and brush with melted butter.

4.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.

5.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.

6.Add the flour and beat on low speed until the flour is just combined (do NOT overmix ).

7.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.

8.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. Place one jelly-roll pan in the middle of the oven and the second jelly-roll pan in the bottom third of the oven.

9.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.

10.Carefully peel away the parchment, then turn the parchment over and use it to cover the cakes. Let the cakes cool to room temperature.

Almond Vanilla syrup
(Note: The syrup can be made up to 1 week in advance and kept covered in the refrigerator.)

What you’ll need:

•a small saucepan


½ cup water
⅓ cup granulated sugar
1 Tbsp vanilla
1 Tbsp. almond extract

1.Stir all the syrup ingredients together in the saucepan and bring to a boil.

2.Remove from the heat and let cool to room temperature.

White Chocolate Mousse
(Note: The mousse can be made ahead and refrigerated until you’re ready to use it.)

What you’ll need:

•a small saucepan
•a mixer or handheld mixer


7 ounces Green & Black’s white chocolate, chopped
1 cup plus 3 tbsp. heavy cream (35% cream)
1 Tbsp. cognac (optional)

1.Melt the white chocolate and the 3 tbsp. of heavy cream in a small saucepan.

2.Stir to ensure that it’s smooth and that the chocolate is melted. Add the tablespoon of liqueur to the chocolate and stir. Set aside to cool completely.

3.In the bowl of a stand mixer, whip the remaining 1 cup of heavy cream until soft peaks form.

4.Gently fold the whipped cream into the cooled chocolate to form a mousse.

5.If it’s too thin, refrigerate it for a bit until it’s spreadable.

6.If you’re not going to use it right away, refrigerate until you’re ready to use.

Fresh Raspberry Buttercream
(Note: you may refrigerate it for up to 4 days after making it; simply bring it to room temperature and then beat it briefly to restore its consistency before using.)

What you’ll need:

•a small saucepan
•a candy or instant-read thermometer
•a stand mixer or handheld mixer
•a bowl and a whisk attachment
•rubber spatula


1 cup granulated sugar
¼ cup water
1 tbsp. pure vanilla extract
1 large egg
1 large egg yolk
1¾ sticks unsalted butter, at room temperature
1 1/2 cups fresh raspberries (for a smoother buttercream, puree berries and strain out the seeds)

1.Combine the sugar, water and vanilla bean seeds or extract in a small saucepan and warm over medium heat just until the sugar dissolves.

2.Continue to cook, without stirring, until the syrup reaches 225◦F (107◦C) [*Note: Original recipe indicates a temperature of 255◦F (124◦C), however, when testing the recipe I found that this was too high so we heated to 225◦F and it worked fine] on a candy or instant-read thermometer. Once it reaches that temperature, remove the syrup from the heat.

3.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.

4.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!

5.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).

6.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.

7.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.

8. At this point, add the raspberries and beat for an additional minute or so. If needed, add a few tablespoons of confectioners' sugar to thicken.

9.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).

White Chocolate Glaze
(Note: It’s best to make the glaze right when you’re ready to finish the cake.)

What you’ll need:

•a small saucepan or double boiler


14 ounces Green & Black’s white chocolate, coarsely chopped
3/4 cup heavy cream (35% cream)

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

Assembling the Opéra Cake

(Note: The finished cake should be served slightly chilled. It can be kept in the refrigerator for up to 1 day).

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 10-inch (25-cm) square and one 10 x 5-inch (25 x 12½-cm) rectangle.

Place one square of cake on the baking sheet and moisten it gently with the flavoured syrup.

Spread about two-thirds 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).

Spread the mousse on the top of the last layer of the joconde. Refrigerate for at least two to three hours to give the mousse the opportunity to firm up.

Make the glaze. After it has cooled for 10 minutes, pour/spread it over the top of the chilled cake. (Use an offset spatula to help spread the glaze, but you'll get the smoothest appearance from allowing gravity to spread the glaze as much as possible.) Return to the refrigerator to allow the glaze to set for at least 30 minutes.

Finishing the cake: using a sharp serrated bread knife, dip the knife into very hot (if not boiling) water, and wipe dry. Using a gentle sawing motion, trip the edges of the cake for a clean-cut appearance. Decorate the cake's top with fresh raspberries dipped in melted white chocolate.

Serve the cake slightly chilled.

Yields approximately 20 servings.


MyKitchenInHalfCups said...

That is beautiful. Raspberry was an excellent choice, wish I done it with raspberry!!

glamah16 said...

Just beautiful.

Peabody said...

Mmm, I love the use of raspberry. Very nice.

Karen Baking Soda said...

Elegant! Very nice with the raspberries and look at the specks of vanilla...

steph- whisk/spoon said...

ohhh...fresh raspberry buttercream looks and sounds wonderful!!

Anonymous said...

Lovely Opera Cake!

Eileen (passions to pastry)

Andrea Meyers said...

That looks so beautiful! Thanks for the tip on the white chocolate, as I never seem to find one I like.

Unknown said...

This is just beautiful! I love the contrast between the pink and the while. Lovely.

Judy said...

Looks absolutely gorgeous, and I bet it tastes fantastic as well.

Anonymous said...

he-he! Great minds think like raspberries!! Your and Sher's cakes all look so lovely and I'm thinking I stop at her place for 2nd breakfast and your place for lunch!

Anonymous said...

Really, this looks fabulous, and I appreciate that you explained exactly how you adapted the recipe!

Anita said...

So pretty...I love red and white together! Great job!

Megan said...

It looks perfect! Love the raspberry flavor. Simple yet elegent!

jasmine said...

This is so pretty. Of course I now have "Pretty in Pink" running through my head...Molly Ringwald et al...


Faery said...

Beautiful and looks really yummy I love the fruits on the cake

Anonymous said...

Beautiful, really !!

Christine said...

Wow this is a masterpiece! Beautiful!

Dolores said...

What a beautiful celebration of the raspberry.

Barbara said...

Your cake is so pretty!

Shari@Whisk: a food blog said...

Your cake looks great! I love the treble clefs around it.
Shari@Whisk: a food blog