It's just as well Michael had a big birthday bash last year, because our options were a bit more restricted this time around. We did pretty well: there were presents and fancy crumpets in the morning, Smith & Deli in a park for lunch, followed by a bike ride and afternoon game of Wingspan. He requested black pepper tofu for dinner. In my free moments around the edges, I baked a birthday cake.
Michael picked this one out of Goh and Ottolenghi's Sweet. It looked a little intimidating, but all my lockdown baking had prepared me perfectly for the egg separating, white beating, and cake layering that's needed.
The cake component is an unusual one: it's made mostly from eggs, sugar and chocolate, forming something with the texture of a sponge cake without any of the flour. There's an anxious moment of mixing watery coffee into melted chocolate which creates a very strange, almost rubbery, texture. Unfortunately we couldn't really taste the coffee in the finished cake, so it probably wasn't worth the drama. The best trick is that this layer cake doesn't require any lengthways slicing: it's all achieved by making a huge rectangular sheet of a cake, and dividing it into three stackable rectangles.
In between sponge layers, there's rosewater whipped cream and walnuts. I was wary of the large rosewater dose, but it was balanced out well by the other flavours, and not too perfumey or soapy. The walnuts are an essential counterbalance of crunch and subtle bitterness, but they also prevented the cake-and-cream layers from sticking to each other properly.
The coffee and the construction are well worth reworking, because this is a fabulous cake! It looks fancy without being finicky. We got eight thick slices out of it; each time we'd launch into the cake's light texture with gusto, and be thoroughly satisfied by the time we finished the thick buttery top with its candied walnuts.
(from Yotam Ottolenghi & Helen Goh's Sweet)
6 eggs, yolks and whites separated
215g caster sugar
215g dark chocolate
2 1/2 teaspoons instant coffee granules
50mL hot water
30g caster sugar
380mL double cream
2 1/2 tablespoons icing sugar
1 1/2 tablespoons rosewater
Preheat an oven to 180°C. Line a 35cm x 25cm Swiss roll tin (for me, this was just my regular baking tray) with baking paper, and spray it with oil.
In a small baking tray, spread out 120g walnuts and roast them until fragrant, about 8 minutes. Allow them to cool, roughly chop them, and then set them aside for the final assembly.
Turn the oven up to 200°C.
Gently melt the chocolate using your preferred method. Dissolve the coffee in the hot water. Very gently stir the coffee into the chocolate.
In a large bowl, beat together the egg yolks and caster sugar for several minutes until very pale and fluffy; Ottolenghi and Goh reckon it should triple in volume. In three batches, gently fold the chocolate mixture into these yolks.
Using clean equipment, whisk the egg whites to form stiff peaks. Gently fold the whites into the chocolate mixture. Spread the mixture out in the Swiss roll tin as evenly as you can. Bake for 20 minutes, until the cake is cooked through but not blackening at the edges (it was a close call with mine!). Allow the cake to cool completely.
Line a small baking tray with paper. Place the topping ingredients in a small saucepan over medium heat and cook them, stirring regularly. Gradually, the sugar will melt, coat the walnuts, and turn golden brown. Keep a close eye on the mixture to avoid burning! When all of the sugar is melted and brown, spread the nuts out across the baking tray to cool. When the nuts have cooled, roughly chop them and set them aside for the final assembly.
Whip together the rosewater cream ingredients to form soft peaks, and refrigerate until the final assembly.
To assemble the cake, slice the chocolate cake into three stout rectangles of the same size. Place one layer on a serving plate and spread it with one third of the rosewater cream. Sprinkle over half of the roasted walnuts. Repeat with a second layer each of cake, cream and roasted walnuts. Repeat with the third layer of cake, the remaining rosewater cream, and top with the candied walnuts.