Technical Thursday: Mary's Tiramisu Cake

Well, to say Britain sort of fell apart and almost broke out in riots following Wednesday night's episode of The Great British Bake Off would be a bit of an understatement.

This week was almost certainly GBBO's Red Wedding, leaving the audience a little bit numb.

It's really a bit ridiculous how seriously we - as a nation - take a television series about cake.

For those who've remained blissfully unaware of all the drama, for last night's Showstopper challenge the bakers were asked to produce a Baked Alaska, and on the hottest day of the year. Combining ice cream, sponge and meringue the bakers were faced with several hours of extreme multitasking, and as the temperature in the tent rose as did everyone's stress levels. That's when it all kicked off.

Contestant Diana removed Iain's ice cream from the freezer to make room for her own, and instead of moving it to another freezer or alerting him to what she'd done, she left it unattended on a counter in the sweltering tent. Then this happened when he discovered it:

(GIF SOURCED FROM www.buzzfeed.com)

Oh. My. God.

Iain subsequently reacted with appropriate anger and had his own meltdown, throwing everything away and being forced to present his bin as his Showstopper. Poor Iain. Thanks to incredibly clever - and arguably nasty - editing Diana morphed into a supervillian within minutes and #justiceforiain began trending on Twitter.

With all of this drama at the end of the episode it's easy to forget about the two challenges at the beginning. For the Technical Challenge, the bakers were asked to produce a version of Mary Berry's Tiramisu Cake. I love tiramisu, so as much as I enjoyed making this it was a bit of a challenge exercising self-control and not even trying a bite. I'm already looking forward to making it again in a few months time!

Ingredients:

For the sponge:
4 large free-range eggs
100g caster sugar
100g self-raising flour

For the filling:
1 tablespoon instant coffee
150ml boiling water
100ml brandy
3 x 250g tubs full-fat mascarpone cheese
300ml double cream
3 tablespoons icing sugar, sifted
75g dark chocolate (36% cocoa solids), grated

To decorate:
100g dark chocolate (70% cocoa solids), broken up
2 tablespoons cocoa powder

Method:

Heat your oven to 180C/350F/gas 4, and line a 35 x 25cm Swiss roll tin with baking parchment.

To make the sponge, whisk the eggs and sugar with an electric mixer until the mixture is very pale and thick, and leaves a light trail on the surface when the whisk is lifted. This will take around 7 minutes.

Sift the flour over the whisked mixture and fold in gently using a metal spoon or plastic spatula, taking care not to over mix. Be aware of lumps of flour that get trapped in little pockets of air - try to get rid of them as best you can but don't squash out all the air in the process!

Pour the mixture into the prepared Swiss roll tin and tilt the tin to level the surface.

Bake in the heated oven for 20 minutes until risen, golden and springy to touch. Cool in the tin for 5 minutes before carefully transferring to a wire rack to cool completely.

For the filling, dissolve the coffee in the boiling water and add the brandy. I used a different ratio of brandy to water as the brandy in my parents' cupboard is over 40 years old and ridiculously strong, so I used only 30ml of brandy and made up the rest with boiling water. The kitchen still smelt of brandy for hours afterwards though, even with such a small amount of the stuff! Set aside to cool.

Put the mascarpone cheese in a large bowl and beat until smooth. This only took a few seconds, as any more than that it becomes too soft and completely unspreadable. You need to keep this as firm as possible and able to retain its shape, but still able to spread on crumbly sponge.

Gradually beat in the cream and icing sugar to make a spreadable frosting. Set aside in the fridge until needed.

When the sponge is cold, carefully slice in half, so you have 2 smaller rectangular sponges. Then cut each one horizontally in half so you have 4 thin sponges of equal height. Using the loose base of an 18cm square loose-based cake tin as a guide, cut each rectangle into a square from each thin sponge. Mine were 14cm squares (I used a ruler, obviously…) which gave me plenty of room to manoeuvre them in the tin. You can go bigger if you dare! Discard the sponge trimmings.

Now gather everything you need to assemble the cake. Line the base and sides of the square tin with baking paper, ensuring that there's plenty over the sides to help when lifting the finished cake out of the tin.

Set one sponge square in the base. Spoon/brush a quarter of the coffee mixture evenly over the sponge to moisten, then spread a quarter of the frosting over the sponge. Scatter a third of the grated chocolate over the frosting. Lay a second sponge square on top and repeat the process until topping with the final sponge.

Spoon over the remaining coffee mixture and using a palette knife spread a very thin layer of the remaining frosting over the cake to create a 'crumb coat' that will seal in any loose crumbs of sponge. Chill for at least an hour in the fridge.

Meanwhile, melt 50g of the broken-up chocolate in a small heatproof bowl set over a pan of gently simmering water. Gently stir the chocolate until it reaches a melting temperature of 55C. Remove the bowl from the pan. Add the remaining chocolate and continue stirring gently until the chocolate cools to 31C or lower and is thick enough to pipe.

Spoon the melted chocolate into a small paper piping bag. Snip off the end. Pipe 9 - or more in case some break - decorative shapes (fleur de lys, for example) onto a sheet of baking paper or a silicone mat. I displayed my shoddy piping skills by piping loads of shapes like the ones in the GBBO book, but they all ended up too thin to use, so make sure you do them thicker than this! Leave to set until required.

Remove the cake from the fridge, neaten up the edges and spread the remaining frosting over the top and sides.

Dust the top with cocoa powder before turning out onto a serving plate. Decorate with the chocolate shapes (if you have any to use…).

Well there you have it: this week's Technical Challenge! Apologies for the lateness of the post and the slightly dodgy photos: yesterday was beyond hectic and I was baking into the night t finish it!

It seemed to work okay… I didn't use enough of the coffee mixture as I was concerned about over filling the cake and making each layer incredibly soggy, but I was obviously over-cautious as patches of the sponge weren't soaked though at all. Also, apparently the coffee flavour doesn't come through much and is overpowered by the chocolate. I'm assuming this is because I used less brandy and topped up the mixture with hot water to make sure I had the right volume of liquid. Maybe I should have added more instant coffee to make up for this and then the flavour wouldn't be so diluted?

That being said, I'm not too disappointed! Let me know if you try out any recipes from this week's GBBO in the comments below!