Birthday Cake for Lou

When I asked my older niece Lou if she fancied a themed cake, she said she didn't mind. And having followed the second season of the Great British Bake Off, I decided to go straight for the most fantastic thing I saw there - the Chocolate and Orange Mousse cake! This was such a beautiful and original piece of edible art work and such an interesting method of making, I felt no hesitation at having a go at it.



The basic idea is to make two thin rectangular sponges from joconde. From these two rounds and two strips are cut out and put together to form a circular box. The middle is filled with the chocolate mousse. The interesting part is that a joconde paste is first made and coloured. It is then piped in swirls onto paper lined baking trays and these are put in the freezer until the paste has frozen solid. This ensures that the pattern remains when the main sponge mixture is poured over it.

Joconde Paste Ingredients

50 g unsalted soft butter, and some melted butter for brushing the baking sheets, about 15 g

50 g sifted icing sugar

50 g egg whites (about 2) at room temperature

55 g sifted plain flour
food colouring

Method

1. Cream the butter, icing sugar until fluffy.
2. Add the egg whites slowly, while still whisking.
3. Fold carefully in the flour.
4. Add food colouring as desired.
5. Brush melted butter onto two shallow baking tins (45 x 30 cm with an edge!).
6. Place baking paper on top and make sure there are no air bubbles or folds on it.
7. Pipe the paste in swirls and place in the freezer for about 1 h.

Joconde Sponge Ingredients

180 g egg whites at room temperature (about 6)
25 g granulated sugar

225 g ground almonds

225 g sifted icing sugar

6 eggs at room temperature

40 g sifted plain flour

40 g sifted cocoa powder for baking

85 g melted and clarified butter

Method

1. Pre-heat the oven to 220 degrees C.
2. Whisk the egg whites until soft peaks stage, then add the granulated sugar and whisk further until stiff peaks form. Cover with cling film to prevent it collapsing and set aside.
3. In a separate bowl, whisk almonds, icing sugar and eggs until pale and fluffy. Then add the flour and the cocoa powder while still whisking.
4. Carefully fold in the meringue into the mixture.
5. Mix about a cup of the sponge mixture into the clarified butter, then add the butter mixture into the sponge.
6. Remove the baking trays with the joconde paste from the freezer and pour the sponge over the swirls in a thin layer, about 1 cm thick, level carefully and bake for 5 - 7 minutes until the sponges have coloured lightly (will be difficult to see, since they are chocolate coloured to begin with).
   
   
7. Once out of the oven, place a sheet of grease proof paper over each baking tray, then turn over the tray to release the sponge. Remove the grease proof paper the sponge was baked in. This reveals the pattern. Let the sponges cool a bit.
   
   

Chocolate Orange Mousse Ingredients

zest and juice of one orange

2 tbsp powdered gelatine

175 g melted plain chocolate

2 eggs separated

300 ml whipped double cream

Final Decoration Ingredients

300 ml whipped double cream

strips of orange zest

Method

1. Strain the orange juice, then dissolve the gelatine in it, using the instructions on the packet.
2. In a separate bowl, mix the zest and chocolate with the egg yolks.
3. Add the orange juice with the gelatine.
4. Whip the whites to stiff peaks and fold gently into the chocolate mixture.
5. Whip the cream to soft peaks and fold into the chocolate mixture.
6. Cut out two circles and two or three narrow strips from the sponges. The cake needs to be built inside a round cake tin - the circles should be a couple of cm smaller in diameter than the cake tin.
   
   
7. Place one circle at the bottom of the round tin, fit the strips around the sides, making sure there are no gaps anywhere.
8. Pour in the chocolate orange mousse, then cover with the second circle. Cover and refrigerate until required.
9. Just before serving, decorate by piping whipped cream and cut out twirls of orange zest.

Now for some reason, the recipe published on the BBC web site was missing the instruction to place the swirl patterns in the freezer. But I'd seen the show, so I know that this needed to be done.

What was a more unpleasant surprise was that the orange joconde paste resulted in some 4 - 5 times more than I actually needed. I have adjusted the recipe above accordingly, but I also have three more batches of orange joconde paste in the freezer for future practice.

I also gravely mis-judged the sponge and opted for making a slightly smaller, but taller cake. Unfortunately the amount of mousse I ended up with was far from enough and you can see the 3 cm of edge I had to cut off because of this. I don't see how this amount would fit in the larger cake described on the BBC web site. Having said that, the double cream exhibited some massively unexpected behaviour. I have whipped double cream in the past and it has worked fine, I just would get slightly less volume. But this time, within seconds it almost turned to butter. So the mousse didn't perhaps get the volume it was supposed to have. At serving time the next day, Lundulph had to whip the remaining cream by hand and again after a few beats with a balloon whisk, the thing had gone to stiff peaks. Really not sure what happened there, it wasn't out of date, I checked!

There was also the issue of baking: 5 - 7 minutes just didn't seem enough and I ended up baking for almost 15 minutes. This was a mistake, as it resulted in a drier sponge, which cracked at the patterns, when I fitted it into the cake tin. Could also have been that I made a smaller diameter cake of course. So don't get tempted to leave it baking for longer!

I also decided to skip one part of the decoration - a layer of gelatine made with orange juice. On the show, it was yellow, not orange and I didn't think it added any value to this otherwise so very impressive cake.

As always, I do not use enough gelatine to make things firm up and so, after Lou cut the first piece, the mousse just poured out like some sort of goo. I have tried to adjust the recipe above for that as well.

On the whole it was a very tasty cake actually and disappeared in the usual manner when we celebrate a family birthday.

Lundulph had some good ideas - he thought this would be really great to do with green swirls and chocolate mint ice cream as filling. I concur and so I will make a second attempt in a couple of weeks when he comes over to visit.

An idea that occurred to me is that you could plan ahead and draw specific patterns on the greaseproof paper that lines the baking tin and even write words on it. But you must do that in mirror writing. Then when you turn it out, the writing will be incorporated into the sponge. So I might try that as well. There seem so many possibilities on this technique.

The many off-cuts from the sponge went into a big box in the fridge for snacking purposes and lasted well over two weeks after the initial baking and very little staleness was noticeable. What I didn't do was to try and freeze some of it, to see how it reacts to that. So that I know if I need to take out a cake with ice cream filling early or at last minute before serving. Well, I'll find out soon enough.