12 May 2008

Opera Cake - Daring Bakers May 2008 Challenge

Well, this is my third Daring Bakers challenge and the best one so far, I think.

Final result

Though part of the reason for this is that the quantities of the previous challenges were way too big for me and Lundulph, we just finished the cheesecake pops the other day and most of the perfect party cake is still in the freezer. So this time I decided to reduce the recipe to a third of the original size. This produced a decent sized cake, that would serve 8 - 9 people.

The Opera cake is a layered cake with buttercream and ganache and a glaze on top. The sponges are called joconde and are moistened by a flavoured syrup.

So without further ado, here it is - light coloured Opera cake.

Joconde Ingredients

2 large egg whites
10 g granulated sugar
75 g ground almonds
1.2 dl icing sugar
2 large eggs
20 g plain flour
1 tbsp unsalted butter, melted and cooled + some for the baking sheet

Joconde Method

  1. Preheat the oven at gas mark 7 (220 degrees C).

  2. Line a deepish sheet with baking parchment and brush with melted butter, not forgetting the sides. A 27 x 31 cm baking sheet gives a 1.5 cm thick joconde.

  3. Beat the egg whites to soft peak stage, then add the granulated sugar and continue beating to hard peak stage. Set the meringue aside.

  4. In a separate bowl, whisk together the ground almonds, icing sugar and eggs until light and fluffy, about 3 minutes on high.

  5. Switch to low speed and add the flour, whisk just long enough to incorporate it.

  6. Gently fold in the meringue, follwed by the butter.

  7. Pour into the baking sheet and bake in the middle of the oven until golden brown, about 15 minutes.

  8. Unmould immediately onto another piece of baking parchment and remove the parchment the joconde baked in. If it's a bit sticky, wet it with a little bit of water. Leave the joconde to cool.
Syrup Ingredients

30 g water
20 g granulated sugar
1 tbsp flavouring of choice, I used vanilla extract

Syrup Method

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

  2. Remove from the heat and leave to cool.
Buttercream Ingredients

35 g granulated sugar
20 g water
1 tsp vanilla extract
1 large egg
70 g unsalted butter at room temperature
1 tsp flavouring of choice, I used dark rhum

Buttercream Method

  1. Combine sugar, water and vanilla extract in a saucepan and bring to the boil on medium heat. Continue until the mixture reaches 107 degrees C. It's a very small amunt so may be difficult to measure. 107 degrees C is just under the so called thread stage, so this could be used instead of thermometer. The original recipe calls for 124 degrees C which is just over soft ball stage. Remove from the heat when the desired temperature has been reached.

  2. In the mean time, whisk the egg at high speed until pale and foamy.

  3. Reduce the mixer speed to low and very slowly pour the hot syrup into the egg foam, avoiding pouring it directly onto the whisks themselves, or it'll fly off to th sides and go solid.

  4. Increase the mixer speed to high again and continue to whisk until smooth and satin looking and cool to the touch. With such a small quantity this shouldn't take long at all.

  5. Once again reduce the speed to low and carefully incorporate the soft butter, a little at a time.

  6. Go back up to high speed and beat until thick and shiny, then add your chosen flavouring and beat for another minute.

  7. Refrigerate for 20 minutes to firm it up for spreading. Stir occasionally.
When I made this, as soon as I started to add the butter, the whole thing collapsed and went rather lumpy.

Curdled buttercream

When I took it out of the fridge, it had released some liquid as well.

Cooling didn't help

White Chocolate Ganache/Mousse Ingredients

70 g white chocolate
2.4 dl + 3 tbsp double cream
1 tbsp liqueur of choice, I used amaretto

White Chocolate Ganache/Mousse Method

  1. Melt the chocolate and the 3 tbsp cream in a saucepan on low heat, stirring until the chocolate has melted completely and the mixture is smooth.

  2. Take off the heat, stir in the liqueur and set aside to cool.

  3. In a separate bowl, whip the 2.4 dl cream to soft peaks stage.

  4. Gently fold in the whipped cream in the the cool shocolate mix to form a mousse.

  5. If it's too runny, refrigerate for 30 minutes to make it firm.
This is the first time I've made ganache or mousse and I generally don't like amaretto, the only reason I used it was to echo the flavour of the joconde. I wasn't sure if it would work at all with white chocolate. As it turned out, it was a very good combination.

Glaze Ingredients

140 g white chocolate
1.2 dl double cream

Glaze Method

  1. Melt the chocolate and the cream in a bain marie, whisking until the chocolate has melted completely and the mixtue is smooth.

  2. Leave to cool completely. If it still feels too runny, refrigerate for 15 - 20 minutes.
Because of the buttercream not being enough, I was a bit worried that the same might happen with the glaze, so I made the double of the above listed dose. This turned out to be a miscalculation on my part, since there was loads left over. It's ever so tasty of course and can be used for other things too.

Cake Constructon

  1. Cut the joconde into three equal sized parts.

  2. Place one part on a cake plate and moisten with one third of the syrup.

  3. Spread the buttercream over the joconde and place the second joconde part on top, moistening with the second third of the syrup. Refrigerate for at least 30 minutes.

  4. Only enough for one layer

  5. Spread half of the ganche/mousse over the second joconde, then cover with the last part of the joconde, moisten with syrup and spread the second half of the ganache/mousse, then refrigerate again for about 1 hour.

  6. Ready to be chilled

  7. Finally pour the glaze over the cake and smooth with a spatula, then refrigerate to firm up the glaze.

  8. Glaze too runny

    The original cake should have two layers of buttercream and one layer of ganache/mousse, but because my buttercream curdled, there was just about enough for one layer. The mousse was quite sufficient for two layers, so this worked out nicely. Unfortunately, the glaze was way too runny and most of it disappeared down the sides of the cake and I managed to scrape off most of it away. Perhaps I'd used more cream in the glaze than the recipe called for, I didn't measure it too precisely. Also the idea of the cake is to see the layerings, so it would be a good idea, after the cake has been completed, to trim the sides to enhance this effect. To cut the cake, a large, sharp knife should be heated up a bit. This will ensure there is no smudging between the layers. The knife can either be heated up under the hot water tap, making sure it's completely dry before cutting, or over the flame of the gas hob, taking care not to overheat it, or it'll melt the creams of the cake.

    The above recipe yields 7 - 9 portions and combines nicely with tangy fruits like physalis. Because there was barely any glaze left on the cake, I used it as a sauce. This was before I'd refrigerated it and realised that it firmed up quite nicely.

    Final result
Most of the parts I made a day or two in advance as constructing the cake takes quite a few hours as well. It's best served chilled.


Shari said...

That little gooseberry looks so cute next to your opera cake!
Shari@Whisk: a food blog

Caramella Mou said...

Hi Shari,

thanks, it worked out very well with the cake too, flavour-wise, as it was quite tart and was a very good offset to the sweetness of the cake.


Dolores said...

Great job with your Opera cake. I've also found some of these recipes need re-sizing so that I can retain *my* size. :)