Unconventional Opera Cake

From my understanding, the traditional opera cake is made up of almond joconde, coffee syrup and buttercream, with chocolate glaze. This is my first entry as an official Daring Baker, and the challenge this month was to make an opera cake without using dark colors, in support of LiveSTRONG Day (May 13th, but I think asking everyone to bake this cake within 2 weeks would have been pushing it).

I didn't want to complicate the cake with too many flavors, so I picked four main ingredients: white chocolate, raspberries, lemons, and hazelnuts. Made the hazelnut joconde on two half-sized baking sheets, so I ended up with 4 layers of cake (each sheet cut in half). After pulling it out of the oven and letting it cool, I brushed them with simple lemon syrup and let that soak in for a few minutes. The white chocolate/black raspberry whipped ganache and the lemon buttercream had been made a couple days in advance and stored in the fridge, so I let those come to room temperature, poked around at them with forks until they were nice and soft, then spread them on. Easy enough to spread, I just took a while to make sure it was all nice and flat. The layer order ended up being joconde, whipped ganache, joconde, buttercream, joconde, buttercream, joconde, buttercream, glaze.

The glaze turned darker than I intended, but it's not too bad. I was surprised at how shiny it actually turned out...it reflects the light! Made some simple designs on top, froze the cake for about half an hour, then cut the edges off with a hot knife to give the final creation:

This picture gets a little closer to the layers, so the divisions can be better seen. It came out a little blurry. I had to borrow a camera that I don't know how to use too well. I bought a camera recently, but this was taken before that. Anyways, you can see how nice and glossy the glaze came out. The stand mixer has its reflection in the glaze (and you KNOW you love my townhouse's carpet...70's shag, woot!).

This ended up being part of my mom's mother's day present. It made me extremely happy when I brought it out, and she thought my brother and I had bought it from the bakery up the street.

Hazelnut Joconde
6 large egg whites, room temperature
2 T. granulated sugar
2 c. hazelnut meal
2 c. icing sugar, sifted
6 large eggs, room temperature
1/2 c. all-purpose flour
3 T. butter, melted and cooled slightly

Divide the oven into thirds, and heated to 425ºF. Line two half-sheet baking trays with parchment paper, then brush with the melted butter. In a stand mixer, beat the egg whites until soft peaks form. Add the granulated sugar, beat until soft and glossy. Scrape this mix into another bowl and set aside. Clean out mixing bowl, then add hazelnuts and sift in the icing sugar. Add the eggs, then with the paddle attachment, beat on medium speed until lighter in color and increased in size (approximately 5 minutes). Add flour, and with a plastic spatula, fold in until just combined (think Muffin Method!), and let sit 10 minutes or so to fully combine. Fold in the meringue, followed by the remaining melted butter. Divide evenly between the two sheets, then spread evenly over the pan. Bake until lightly browned and spongy (5 minutes for the top cake, 7 for the bottom one, but that's using my oven...check frequently). Take another baking sheet and place a piece of parchment paper on the bottom, set this on top of the finished cake, and invert to release from mold. Remove the buttered piece of parchment paper and flip upside-down, so the dry side is against the cake (remove slowly so the cake doesn't tear). Allow to cool to room temperature.

Lemon Syrup
1/2 c. water
1/3 c. sugar
Juice of 1 small lemon

Bring ingredients to a boil, allow to cool to room temperature. Can be stored in the fridge for several days.

Lemon Buttercream
2 c. sugar
1/2 c. water
1 3/4 c. butter, room temperature (I said it tastes good, not that it's healthy)
1 egg, room temperature
1 egg yolk, room temperature
1/2 T. vanilla extract
Juice of 2 small lemons

Combine sugar, water, and vanilla in a small saucepan, warm over medium heat until fully dissolved. Increase heat and, monitoring by candy thermometer, heat to 230ºF. Do not stir while this is heating. In the meantime, whisk the egg and egg yolk in stand mixer until pale and foamy. Slow the speed of the mixer, and very slowly pour the syrup into the bowl, taking care not to touch the whisk. After the last of the syrup has been added, increase whisking speed to medium-high until the mixture is thick, satiny, and cool to the touch (7 minutes). In the meantime, place butter into a bowl and mash with a spatula or spoon until softened and creamy. Once the whisking mix is cool to the touch, add the butter in 2T portions. Don't add another portion until the previous portion is fully consumed by the mixture. When it is all combined, raise speed and beat until thick and shiny. Add the lemon juice, beat for another minute. It should be rather thick at this point, but if it is not, place into the refrigerator. Can be stored for a few days.

White Chocolate and Black Raspberry Ganache-Mousse
7 oz. white chocolate, chopped
1 c. + 3 T. heavy cream
1 T. Bailey's
2 1/2 T. black raspberry purée

Take frozen black raspberries, place into a food processor, and chop/grind until purée forms (you can pass this through a fine mesh sieve to remove the seeds at this point, but I got no complaints for skipping this). Place 3 T. heavy cream into a small saucepan and add the white chocolate. Stir until smooth and melted, then add the Bailey's and black raspberry purée, stir, and set aside to cool. Whip the remaining cream in stand mixer until soft peaks form. Carefully fold the whipped cream into the cooled chocolate to form mousse. This can be cooled and stored in the refrigerator for a few days.

White Chocolate and Black Raspberry Glaze
14 oz. white chocolate, chopped
1/2 c. heavy cream
1 1/2 T. black raspberry purée (or more to taste)

Heat and stir until smooth, remove from heat and add black raspberry purée. Cool for 10 minutes. This should be made just before the assembly of the cake.

Assembly
If the buttercream and ganache-mousse have been stored in the fridge up to this point, allow them to return to room temperature. The buttercream may need some stirring with a fork to return it to the correct consistency.

Cut the two cooled hazelnut joconde pieces in half, forming 4 pieces of approximately the same size. Brush the joconde with lemon syrup (use all of it; it will soak fully). On a cutting board lined with parchment paper, carefully slide into place one of the joconde pieces. Spoon on the ganache-mousse, and spread evenly with a long knife or spatula. Carefully slide on top another piece of joconde. Divide buttercream into three portions, and spread one portion evenly on top of this joconde layer. Repeat until all joconde and buttercream is used. Freeze the cake for a few minutes, then remove from freezer and pour glaze on top (I did not use all of the glaze, as it started running all over the place). Decorate as desired, then place back into the freezer. Cool for 30 minutes, then with a hot knife, cut edges away to give the cake the iconic clean-face look. Remove from the parchment paper and place onto serving tray (it should be hardened by this point, and can be moved easily with a spatula). After edges had been cut away, my cake was able to be sliced into 16 thin slices...some people were fine with eating one, others had two, so it probably serves about 10. Leftover edges are delicious to snack on while the cake is taunting you to dig in.

Be careful when placing the glazed cake in the freezer. I lined the shelf with the leftover parchment paper that was removed from the joconde, because the glaze was sliding all over the place. Once the glaze is cold and cut, it is not an issue, and I stored this in the refrigerator. Remove and allow to come to room temperature, or slightly below it, before cutting and serving.