Coconut and white chocolate opera cake
Sacrilege? Somewhat – I do like to make my first attempts at something to either be the traditional version or from a recipe akin to a traditional version. I should have made my first opera cake using dark chocolate and espresso, but the theme for Baking Society’s weekly meeting was white chocolate, so I had to think about flavour combinations! Coconut popped into my head first, although while baking I also thought pistachio or green tea would have been fun as I’d then get some variation in colour. While I had the right ingredients in the kitchen to do this, I didn’t want to suddenly change my mind. White chocolate and coconut it was.
I essentially followed this recipe by Nic and Rosso of My Kitchen Rules fame, but with coconut essence and water in place of espresso, white chocolate in place of dark chocolate, and coconut in place of cocoa. It actually wasn’t that difficult, once I’d rescued the buttercream icing! A minor moment of disaster, averted by whipping it (so easy, but I had to Google to check!) and assembly was complete!
So there are four almond sponge cake layers (“joconde” apparently) that have been soaked in a coconut syrup, and sandwiched together with alternate layers of coconut flavoured buttercream and white chocolate ganache. I then topped it with some desiccated coconut, and trimmed the sides to show off the gorgeous layers. Clearly I don’t have the most perfect layers, but I’m happy with how they look and am sure I’ll make everything more even the second time I make this. There are far too many ingredients and components to tell you what to do and with what at the same time, so here we have a more traditional appearing recipe style post!
Almond sponge cake
40g unsalted butter, melted
180g icing sugar, sifted
180g ground almonds, sifted
35g gluten-free flour*, sifted
5 egg whites
55g caster sugar
As per the original recipe – mix the whole eggs until thick and creamy and add the melted butter. Fold in the icing sugar, ground almonds and flour. The thicker and creamier the eggs become, the more air that will go into the mix, and so once you add the dry ingredients it will still be a light and fluffy texture. In a separate bowl, whip the egg whites, gradually adding the caster sugar until soft peaks form. While doing this I realised that I really needed a second big mixing bowl as I ended up with egg whites all over the kitchen bench. I ended up using 6 egg whites as an estimate of how much was whipped out of the bowl initially. Of course if I had just used my normal mixer here, I doubt it would have happened. Instead, I used the whipping attachment to my StickMixer Pro (I don’t have the blender component as it was exceptionally difficult to clean, had food stuck inside it and subsequently stunk. It ended up in the rubbish bin a long time ago and was replaced with a Bamix. I’m not sure if Sunbeam has updated the model, but hopefully they’ve addressed the cleaning/food stuck/smell issue as I wasn’t the only one who had that problem). Pour mixture equally into two lined trays and bake for 15 – 20 minutes at 200°C. I know that the original recipe recommended 15 minutes, but I found that this produced a sponge that was light and cooked, but also difficult to handle as it would split into two more easily. My 20 minute tray was a lot easier to handle, and I don’t think it really lost any textural qualities.
Almond sponge with lots of air pockets to take up the coconut syrup
*You could just use ordinary flour. If you wish to use gluten-free flour, my cake flour mix consists of 2 cups brown rice flour, 1 cup white rice flour, 1 cup of potato starch (referred to as potato flour here in Australia), ½ cup of tapioca flour (aka arrowroot) and 1¼ tsp xanthan gum.
I ended up with a lot of syrup and would likely make the second quantities of water and sugar 100mL and 80g in future batches.
130g caster sugar
Approx. 3 tsp coconut essence
200 mL water
165g caster sugar
First, my ingredient list is not an error – I’m just saving you the hassle of calculating 295 minus 130. Second, I recommend that you make both the coconut syrup and buttercream at the same time – it saves you washing one bowl. As you use a lot of of bowls and utensils to make this cake, I will save washing up where possible. Even if it is just the one bowl. Place 125mL water, 130g caster sugar and coconut essence in a small saucepan over medium heat. I never stir my sugar and water mixes when heating them on the stove. Not sure why, I just don’t. Once the sugar has dissolved, reduce heat and simmer until thick and syrupy. Set aside 80mL (or just put directly into buttercream mix), add remaining caster sugar and water and cook over medium heat until sugar dissolves and comes to the boil. Remove from heat and allow to cool.
150g caster sugar
3 egg yolks
250g unsalted butter, chopped, at room temperature
This was a lot of fun in the sense that I didn’t read the recipe properly (or was impatient) and subsequently ended up with a very liquidy concoction. While I got there in the end, I suspect that I would just repeat what I did rather than follow the recipe properly. So, as a reminder, here is the original recipe. Now we proceed my way.
Combine sugar and 100ml water in a small saucepan over medium heat until sugar dissolves. Boil rapidly for 10 minutes. In a clean bowl, whisk egg yolks until smooth, then add the hot syrup until combined. This will effectively cook the egg yolks (or you can tell yourself that if you’re concerned about using raw eggs in cooking). Add the 80mL syrup from the coconut syrup component and whisk in the butter, 1 cube at a time. Place in fridge to cool. Once the mix has thickened considerably, you can whip it up. It will lighten in colour and become a gorgeous fluffy mixture. I don’t know about you, but as someone who loves friands/financiers and macarons, and hates sifting, I will be making this style of buttercream for icing in the future rather than combining butter and icing sugar.
300ml thickened cream
400g white chocolate, broken into squares
20g unsalted butter, softened
I love ganache. It’s so easy to prepare! I also tend to make a lot of it, as everyone should love ganache. Bring cream to boil in a small saucepan. Remove from heat, and add chocolate and butter. Stir until smooth and place in fridge to cool. Once the mix has thickened considerably, you can whip it up. Easy. Yum.
Cut sponge layers into two so you end up with four pieces of approximately similar shape and size. Spread 60g of melted white chocolate on the side of one of the layers and allow it to set. Turn over and brush coconut syrup liberally over layer. Spread half of the buttercream onto the layer and top with another piece of the sponge. Brush with coconut syrup, spread half of the ganache onto it. Repeat the process with your third layer of sponge, coconut syrup, buttercream, fourth layer of sponge, coconut syrup and ganache. Trim edges so you end up with a neat looking cube and cover with desiccated coconut. Done! Eat trimmed layers with a strong cup of coffee or tea as it is very sweet.
Trimmings – which I had for breakfast the next day. Oops.
Pre-cut pieces ready for transport thanks to Decor and Sistema working together!