Two days ago, walking home from doing moderately strenuous exercise at my old junior high, my sister and I caught a fruity scent in the winds. Much to our surprise, we looked down and found fallen, bruised star fruits on the pavement. There had been a wild fruit tree behind our house and we never knew for 10+ years. We (well, me) jumped as high as we could but could only literally get the low-hanging fruit, the baby ones.
Having two homes on either sides of the equator is a curious thing. It means that instead of spending Christmas in the heat waves of Australia, we get to experience winter twice. Not that it gets particularly winter-y here for the best part of December and even January, but I am one that prefers slightly cooler weather. Something having to do with hot baths, I imagine, but it is also excellent conditions for baking. Instead of standing in 40C Australian kitchen watching room temperature butter melt and fighting away flies, I can do what I like most in peaceful solitude.
The cake came out really well, I thought, the tangy buttercream refreshing against the dark chocolate and roasted almond. I could’ve just made the buttercream and be more than satisfied, but now there’s a whole cake to go with it! You don’t have to use roasted almond meal, of course, as it has a much more pronounced flavour than raw, I’m just going through an obsessive phase with that stuff right now.
lemony opera cake (6 servings)
For the joconde:
83g almond meal (I roasted mine beforehand, just to experiment)
50g icing sugar
80g whole eggs
16g cake flour
2 egg whites
For the lemon ganache:
55g dark chocolate (or mixture of dark & milk)
35g heavy cream
10g fresh lemon juice
For the lemon buttercream:
2 egg yolks
15g heavy cream
30g lemon juice
150g unsalted butter
25g egg whites
vanilla extract and salt to taste
For the base chocolate:
60g dark chocolate
1 tsp flavourless oil
For the soaking syrup:
1tsp lemon zest
For the chocolate glaze:
100g dark chocolate
170g heavy cream
15g unsalted butter
Preheat the oven to 180C and line an eighth sheet pan (or 24 x 34 cm). To make the joconde biscuit, sift the almond meal and icing sugar together, and whisk in the eggs, followed by sifted cake flour. Melt the butter and leave to cool. Beat the egg whites until foamy and gradually add the sugar to form medium-stiff peaks. Introduce the whites to the almond mixture in stages, trickling in the cooled butter, and mix until just even. Spread onto the sheet pan and bake for approx. 10 minutes until the centre springs back to the gentle touch. Lift out cake with parchment and cool completely on wire rack before slicing into 3 equal rectangles (cuts parallel with shorter edges).
For the ganache, boil the cream and lemon juice and pour over the chopped chocolate. Don’t disturb for a minute then stir to mix, add honey and butter, mix again. Cover and set aside at room temperature.
For the buttercream, whisk the yolks with half (40g) the sugar until the sugar has dissolved and the mixture has turned pale and fluffy. Boil the cream and lemon juice in a pot, and slowly stream into the yolk mixture while whisking the yolks constantly. Pour everything back into pot and whisk on low heat until the mixture reaches 82C, or thickened to leave an open channel when you drag a finger through the back of your spoon/spatula. Put plastic wrap directly on the surface and cool completely. Beat the butter until lightened in colour and airy, then add in the cooled lemon curd and beat together. Make an Italian meringue with the egg whites and remaining 40g of sugar by beating the egg whites to soft peaks and slowly adding sugar syrup (sugar cooked with enough water just to wet it to 115C) while still mixing, and whisk further until stiff peaks form and the bowl is no longer hot. Fold the meringue into the butter and lemon curd mixture, cover and set aside at room temperature.
Add the oil to the melted dark chocolate to make the base chocolate.
Boil the water and sugar together, then add in the zest. Cool to room temp.
For a simple glaze (traditionally a mirror glaze but I’m opting for a ganache type glaze to make a pattern), boil cream and pour onto chopped chocolate. Stir to combine, add butter, stir again.
Assembly: brush the bottom of one of the joconde strips with the base chocolate, in an even thin layer. Flip the strip upside down so the melted chocolate is in contact with a lined surface. Chill to set the chocolate. Then, brush the cake with lemon syrup, and spread half of the buttercream on top in an even layer, about as thick as the cake layer. Gently place a second strip of cake on top and chill to set the buttercream. Once set, brush the second piece of cake with syrup, and spread the lemon ganache on top (should be spreadable, not runny or solid). Place another piece of cake on top. Chill to harden ganache. Brush on syrup. Spread on the remaining buttercream (needs to be as smooth and even as possible, especially if just pouring glaze on top and not making a design like I did). Chill the entire cake thoroughly before pouring the glaze. Warm the glaze to about 44C, and pour over the entire cake. Quickly level out with a straight spatula twice (back and forth). Should set almost immediately if the cake is cold. Trim off the edges to reveal the layers and cut to desired sized pieces.