Being a foodie at heart, also being Jewish has always been a bit of a culinary thorn in my side, especially also being half Chinese. Even though I'm quite secular in my ways, I keep kosher (more or less- the main parts, like not eating pork or shellfish) out of respect for my family. The most irritating thing has always been not being able to use gelatine, which rules out things like mousses, no-bake cheesecake, home made jellies, panna cotta and more. Agar-agar (seaweed jelly) and fish gelatine are all well and good, but the former gives quite a different texture, and both can't be used as direct substitutes in recipes when it comes to quantities. At last, my search for a viable alternative as at an end.
This was a quadruple challenge for me: firstly, I've never made a genoise sponge. Secondly, I've never used real gelatine. Thirdly, I've never tried making a jelly layer on top of a cake. Finally, I've never built a tall, moulded cake before. I had to do lots and lots of research to make sure I was getting my quantities right- especially for the mousse layer. I think I did alright.
Eating this cake is like eating a strawberry cloud. The genoise is light and fluffy, the mousse is fruity and, well, moussy, and the jewel-like strawberry jelly topping makes the whole thing feel rather special. I'm not going to lie: this cake requires your time and love, and is not a cake to make if you're in a hurry. I'd recommend you make this the day before you want to eat it, as the mousse and jelly layer take quite a few hours to set. What I did was make the sponge the day before and wrapped it up in clingfilm to keep it moist, and then made the mousse filling and assembled it the following morning to be eaten in the evening.
Also, this recipe uses a lot of strawberries. You'll need all 300g of the puréed strawberries, but you might have some of the halved and sliced ones left over, depending on how big your strawberries are and how much area they cover during decorating. In any case, it's better to have a little more just in case.
Ingredients for Genoise Sponge:
-5 eggs (no need to separate!)
-180g caster sugar
-120g self-raising flour
-50g cornflour (gives the cake an extra fine texture)
-20g salted butter, melted and cooled
-1tbsp milk (mix this in with the melted butter)
Ingredients for Simple Syrup:
-2tbsp caster sugar
-5tbsp hot water
-1tsp vanilla (or sherry if you have any)
Ingredients for Strawberry Mousse:
-4tsp powdered gelatine* (in my case, Kolatin, but the regular stuff will work too)
-70ml cold water
-300g puréed strawberries
-100g caster sugar
-300ml whipping cream
-1 egg white**
-300g more strawberries, halved
Ingredients for Jelly Layer:
-400g strawberries, sliced
-1 pack strawberry jelly (again I used the kosher kind, but you can use any)
1) Make the genoise first. Preheat the oven to 180 degrees C and line the bottom and sides of a 9" springform baking tin with baking parchment.
2) Sift the two flours together onto a plate to aerate it.
3) Place the eggs and sugar in a large heatproof bowl, and place that bowl over a pan of barely simmering water- not too hot or you'll scramble the eggs. Stir until all the sugar has dissolved and the egg mixture is warm, and take off the heat.
4) Whisk the egg mixture for five to ten minutes until thick and foamy- it's ready when a ribbon of foam can sit on top of the rest of the mixture when you lift the beaters up.
5) VERY GENTLY fold in the sifted flours until well-combined, followed by the butter and milk mixture, taking care not to bash too much air out of your foamy eggs.
6) Pour into your baking tin, drop the tin onto the counter a few times to knock out any giant air bubbles, and bake for about 25mins or until a skewer comes out clean. The top of the cake will be a light golden colour.
7) Immediately turn the tin upside-down onto a cooking rack lined with a bit of baking parchment, and leave the cake to go completely cold inside the tin.
(( At this point you can wrap the cake up in clingfilm if you're continuing the next day. If not, continue on...))
8) Make the simple syrup (also known as soaking syrup in the baking world) by dissolving the sugar in the hot water and adding the vanilla.
9) Unveil your genoise sponge cake, peeling the baking parchment off of it. Slice it into two even layers (I used a long bread knife), and dab the cut sides with the syrup to keep them moist- save a little syrup to brush on top later.
10) Clean out your springform pan and line it with foil this time, making the lining of the sides taller than the tin itself (doubling a long strip of foil makes the structure sturdier). Place one cake layer at the bottom of the pan cut side up.
11) Now you can make the mousse. Place the gelatine in the water in a small bowl and let it soak for a couple of minutes to let the gelatine plump up.
12) Gently warm the strawberry purée in a saucepan and dissolve the sugar and gelatine into it. Take it off the heat to let it cool slightly, almost to room temperature.
13) In two separate bowls, whip up the egg white until it forms stiff peaks (like you would for a meringue), and whip the cream also until stiff. (Do the egg whites first so you don't get any grease in them, which will stop them from getting as foamy as possible.)
14) Fold the strawberry purée mixture into the cream, followed by the egg whites, until thoroughly combined. It'll look a bit thin, but don't panic.
15) Assemble your cake! Arrange as many strawberry halves as you need around the edge of the cake slice in the tin, cut side facing outwards and upside-down. Slice any remaining halves and arrange them on the bottom. It should look something like this:
16) Pour about two thirds of your mousse mixture into the tin, or until it covers the tops of your ring of strawberries.
17) Place the second layer of cake on top cut side down, and brush a little more syrup on top. Pour the rest of the mousse on top of the cake, and put the whole thing in the fridge for four hours.
18) Make the final jelly layer! Follow your package's instructions to make up the jelly liquid, and let it cool for a couple of minutes- not too long or it'll start to set.
19) Take your cake out of the fridge and arrange your sliced strawberries on top. Carefully spoon over your jelly mixture, and put your cake back in the fridge for another two hours.
20) It's time for the grand unveiling! Take the cake out, dip a knife into hot water, dry it and run it around the cake to help loosen it from the foil. Take it out of the springform tin, peel away the foil and- tah dah! You have yourself a fancy strawberry mousse cake.
*I say 4tsp, and I mean it. You need four slightly heaped teaspoons. I went against my own carefully calculated recipe and used three and a half teaspoons. Why? Because that's the quantity in one packet of Kolatin, and I didn't want to open another one for just another half teaspoon. Curse my slight OCD completionist nature! The mousse still came out great, but could have been just a tiny bit firmer. Also, the longer you leave the mousse in the fridge to set, the better.
** This recipe uses a raw egg white. If you're pregnant or otherwise advised against this sort of tomfoolery, use pasteurised: you can buy cartons of pasteurised egg whites at the supermarket, usually where the butter is. You could also leave it out altogether, but you'd lose some of the airiness of the mousse.
Next time I make a mousse cake, I'm going to try it with mango. I can't wait to keep refining the presentation of the cake- it was a little more slapdash that I'm used to by my own standards, but that was more because of the fact that I didn't partition out the middle and top layer of mousse very well: I intended the top to look as it if were a solid layer of mousse, but as you can see there are a few small gaps from not reserving enough mousse for the top layer. Next time it will be PERFECT.