Chocolate Mousse Gâteau

This recipe involves two separate classic culinary techniques: the making of chocolate génoise and the preparation of chocolate mousse. The mousse can be eaten as a pudding in its own right (simply spoon into ramekins or small glasses and chill) and the génoise can also be used in any number of gâteaux, including that old faithful Black Forest My finished product is an adaptation of a sachertorte, but lighter, and the mousse is quite heretical.

In Britain, learning to make a Victoria sponge has always been an essential part of what used to be called domestic science. I am sure this is why people have more difficulty making a génoise. With the widespread use of food mixers, however, achieving a consistent and light result has become child’s play indeed.

It is not intrinsically hard to achieve a light texture but the technique is very different from that for a Victoria sponge. If you have made the Sauternes and Olive Oil Cake successfully then you will not have a problem, for they are very similar in execution. Should your first attempt prove a little dry and heavy, just soak the sponge with some suitable alcohol. It will still be delicious.

Génoise sponges are best baked the day before they are needed as they will slice better after a night’s rest unmoulded, allowed to cool completely and stored in an airtight container. They also freeze well.

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Ingredients

  • For the Chocolate Génoise
  • 55 g/2 oz unsalted butter, plus more for greasing
  • 125 g/ oz fine plain flour, plus more for dusting
  • 5 size 3 eggs
  • 125 g/ oz caster sugar
  • 55 g/2 oz cocoa powder

For the Chocolate Mousse

  • 1 espresso cup of strong freshly made espresso coffee (or strong filter coffee)
  • 125 g/ oz caster sugar
  • 115 g/4 oz best plain chocolate
  • 1 tbsp brandy, rum or whisky
  • 55 g/2 oz unsalted butter
  • 4 size 3 eggs

To Assemble

  • 1 espresso cup of strong freshly made espresso coffee (or strong filter coffee)
  • 1 tbsp caster sugar
  • 1 small glass (3 or 4 tbsp) of brandy, rum or whisky
  • 2 tbsp apricot jam (optional)

Utensils

  • sheet of non-stick baking paper
  • 25 cm / 10 in springform cake pan
  • food mixer
  • rubber spatula
  • sieve
  • 3 bowls
  • saucepan in which one of the bowls will it exactly (so water can be heated underneath it without the bowl actually touching the water)
  • electric beater
  • spatula

Method

Mise en Place

Make the génoise well ahead (ideally the day before): preheat the oven to 150°C/300°F/gas2. Cut the baking paper to fit the bottom of the cake pan and put it in place. With a buttered paper, grease the insides of the cake pan carefully, then dust it lightly with fine plain flour. Shake off any excess.

Make the sponge batter weigh out all the ingredients • Put the eggs and sugar into the bowl of a mixer and beat at a medium speed until it rises. This will take 5-10 minutes and it is very important to incorporate as much air as possible at this stage. Continue to beat until you achieve a ribbon consistency (stiff enough to be able to write in it), when the mixture will be an off-white colour • Put the butter in a pan over a low heat to melt • Sieve the flour and cocoa together into a bowl, then add to the egg mixture in the bowl. Remove the mixer bowl and, with a spatula, stir gently, starting from the centre at the bottom and working outwards and upwards while rotating the bowl one quarter-turn. Repeat 3 more times (which means the bowl will have been turned full circle). This is called 'folding' and is the best way of ensuring all the elements are thoroughly mixed without losing lightness by being heavy-handed. If you over-work the mixture at this point you will end up with a leaden cake • Add the melted butter and incorporate lightly in the same way.

Cooking

Working quickly, pour this mixture into the prepared cake pan, using the spatula to scrape the last of it from the mixing bowl. Bake the sponge for 20-30 minutes, without opening the oven door for at least the first 20 minutes.

Test the cake for doneness by inserting a small clean sharp knife or skewer into the centre of the sponge: if it comes out clean, then the cake is done. If moist bits of sponge adhere to it, bake for another 5 minutes and test again. Test one more time if necessary. When satisfied it is done, transfer to a wire rack to cool.

As soon as you can handle the pan, unclip it and unmould the sponge, which should have doubled in volume during the baking. Leave to cool.

Make the Chocolate Mousse: brew the coffee and dissolve 1 tablespoon of sugar in it while still very hot.

Put some water into a saucepan with a bowl of matching size sitting just above the level of the water. It is important it should not be in direct contact with the water. Heat to a simmer, just below boiling point.

Break the chocolate into pieces and put these with the sweetened espresso and alcohol in the bowl set over the hot water to melt It is vital that the liquid and liquor are put in right at the beginning. If added later, the chocolate will separate. Once the chocolate has melted, stir in the butter to achieve a smooth glossy mixture. Be gentle.

While the chocolate is melting, separate the eggs and put the egg yolks and sugar in a second bowl. Beat until they achieve a ribbon consistency.

Wash the beaters and, in a third bowl, beat the egg whites until they form soft peaks. The texture should not be as stiff as for a meringue, but more of a thick airy foam. Take them too far and the end result will be dry and lifeless.

Using the spatula, scrape the chocolate mixture into the egg yolk and sugar mixture and mix until they are just incorporated.

Now the tricky bit using a large spoon, scoop up some egg white and throw it into this chocolate batter. Stir it in quickly. This gives it an initial lightening. Now scrape all of that chocolate mixture on the egg whites and fold in. Be incisive but gentle, trying to retain as much volume as you can. Inevitably you are going to lose some volume, but do not over-work.

Assembly

Make the second cup of strong espresso coffee, sweeten it with the tablespoon of sugar and add to it a small glass of the same alcohol you put in with the chocolate. If you like the idea of some fruit in the cake, heat the apricot jam with 1 tablespoon of water until dissolved and then sieve and reserve.

Now slice the sponge across horizontally into 4 layers (a bread knife is ideal for this purpose).

Reserve the best-looking slice for the top. Do not put anything on this layer, but brush the other slices with the coffee and alcohol mixture.

Return one layer to the pan in which the cake was baked and brush with the apricot jam glaze, if using. Clip the pan shut around it and spoon over one-third of the chocolate mousse. Put the second layer on top, and spoon on another one-third of the mousse. Repeat with the third layer, and finish with the reserved layer. Do not put anything on the top. Refrigerate overnight.

Serving

While the gâteau needs no further embellishment, I like to make a simple stencil and use it to dust the top with an icing sugar pattern. When ready to serve, unmould the gâteau carefully by sliding a warm palette knife round the inside of the pan before unclipping it Leave it on the base.

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