Chocolate Opera Gateau

I have a list of cakes that I want to try out sitting in my phone. It’s not that long (although there are actually three lists), but it contains all the sleeting bits of inspiration and mad visceral desires that come to me as a result of being a total and incorrigible Cakeophile. There are three cakes like this on my list right now, and they all have one thing in common: They all have coffee buttercream – and the urge to make them was triggered by those utterly delicious Coffee Toffee Crunch Whoopie Pies I posted a couple of weeks ago.

I have a feeling I should apologise about this new obsession with coffee flavoured cake – but I’m not going to – coffee flavoured things are good and worthy of being the centre of an obsession.

It was my actual real and scheduled turn to make morning tea at work this week and to commemorate this special occasion, I wanted to do one of these coffee oriented cakes. I confess I actually wanted to make Opera Gateau, which is a well known French patisserie item which appears to be having a bit of a renaissance right now. However, I had a head cold and was feeling too poorly to commit to the real, intense patissier madness that is Opera Gateau (for example you have to bake many individual layers of cake – and went for a sort of halfway house – a single deep chocolate cake, split into 6 layers, filled alternately with “cheat’s” mousseline buttercream (more on that later) flavoured heavily with coffee and vanilla, then drowned in chocolate ganache.

It’s basically a simple, Chocolate Opera Gateau – or as I like to think of it: Chocolate cake going to the Opera.

A cheeky rosette of coffee buttercream sits happily on top of each piece, and I have to say, it’s as pretty as all get-out. Sometimes I think I make cakes just to look at them. There are your cake makers who are basically experts in moulding clay that happens to be made of food and make Singer Sewing Machines that are apparently cake, and I suppose that is fine, but personally, I am far more in favour of cake that is made to look like CAKE. This Chocolate Opera Gateau falls squarely into the latter category. It is cake, empowered, rather than cake, disguised. You should not hide who you are. And perhaps I am using the term “gateau” in this post to mean cake, empowered. Which probably means I am really a Gateauophile. And if, as it may some day transpire, my favourable thoughts on cake come to be taken as a socio-political view (Gateauminism), I suppose this would make me a Gateauminist. Meantime I  suppose, as a lover of such comestibles, I am just a Gateaunome. Or, some days, a GateauNomNomNomnome. Of course, this is the best thing to be.

I mentioned “cheats” mousseline a moment ago. Mousseline is actually crème patissiere whipped with a hefty amount of butter. It is touted as the lightest of the buttercreams – it’s almost mousse-like (hence its name I guess!), and it is used as a filling in some classic cakes including the Frasier. It’s divine, but it takes time because you need to make real crème patissiere and let it cool (and woe betide ye if it didn’t cool enough! Butter soup!). You will also recall that I have a deep and abiding affection for butter roux frosting, which is a milk and flour roux added to whipped butter and granulated sugar. My Cheat’s Mousseline falls halfway between the two: it has the custard of Mousseline but otherwise the method of butter roux frosting. And it’s doubly cheaty because you can use custard powder to make the custard (in the microwave even). It’s light, not too sweet, and has a wonderful extra depth of taste compared to regular frostings.

Chocolate Opera Gateau

Dark Cocoa Cake

ingredients

mixing

Line a 18cm square cake pan with baking paper.

Place all ingredients except for eggs in a large bowl. Beat until smooth. Add eggs and beat on high for two minutes until light and creamy. Spoon the mixture into the prepared pan and level the batter. Bake at 160 degrees Celsius for about 1 hour 5 minutes or until the cake is firm to the touch. Let cool, then wrap and refrigerate overnight – this makes the cake easier to cut! Trim the top of the cake so that it is flat (if there is a bit of rounding on the edges of the top layer that is OK, you are going to trim the sides anyway, then carefully split the cake into three even layers, then split each layer into two. The layers should be about 6-8 mm thick.

Divide each bowl of cheat’s mousseline into thirds (just flatten the surface and mark thirds in the bowl as a guide- you don’t need to use further bowls!). Starting with the bottom layer of the cake and a third of the vanilla mousseline, spread the mousseline in a thick even layer over the entirety of the cake. Top with the second layer of cake, this time spreading the surface with a third of the coffee mousseline. Repeat until the last layer of the cake has been stacked up. Divide the last third of coffee mousseline into half and spread one half in a thin layer on top of the cake. Load the rest of the coffee mousseline into a piping bag fitted with a small fluted nozzle, then set aside (keep at room temperature!).

Ensure the ganache is at room temperature but still of a pouring consistency similar to liquid honey. Transfer the cake to a wire rack positioned over a deep plate (I didn’t do this because my brain was on the fritz and it was messy!) Pour all of the ganache, all at once, on top of the cake and let it dribble down the sides of the cake. You shouldn’t need to touch the ganache at all for it to cover the entire surface of the cake. Let the cake drip for a while, then transfer the cake to the refrigerator to set.

When the ganache is set (after at least half an hour -test this by touching the sides of the cake, not the top – you will leave fingerprints!) remove the cake from the fridge and transfer to a flat surface to trim the edges. Using a large knife, trim about 8mm-1cm from each side of the cake so that you have beautiful smooth sides with the mousseline layers clearly exposed. The cake should still be square. Using the blade of the knife and just touching the surface of the ganache, gently mark the cake into 16 equal portions (mark the halfway point first, then mark each half into half – or use a ruler if your “eye” is no good at this!).

Pipe a rosette of coffee buttercream in the centre of each (uncut) portion and decorate with a chocolate ball or chocolate coffee bean.

When it comes time to serve the cake, using one firm but slow motion for each cut, cut down the lines marked on the ganache to make 16 portions. I think the portions look best served slightly apart from each other, so that one may gaze lovingly at all those layers. The cake will keep refrigerated in a sealed container for up to a week. You might notice the ganache “sweat” a little when you take it out of the fridge. Don’t worry about it: usually, if you leave the cake at room temperature for a while, that “sweat” will evaporate.

Cheats Mousseline

Obviously if coffee flavour isn’t your thing, there is no reason why you couldn’t substitute in another flavour – for example, if you wanted strawberry, you could use strawberry essence, a couple of tablespoons of strawberry jam, about 50g of crushed  fresh strawberries, or a combination of these to taste. And now I am wishing that I had made a strawberry version. Drat.

ingredients

mixing

In a large microwaveable bowl, mix the custard powder with a little milk until you have a smooth paste, then add the rest of the milk. Microwave the mixture on high for one minute, then stir. Repeat for another minute (custard will be thick) and stir. Cook for a further 30 seconds, then cover with a layer of cling film directly on the surface of the custard and cool to room temperature – this is important, if the flour mixture is too hot the resulting frosting will be soupy! If this happens, chill the mixture and beat again.

Cream the butter and sugar until light and fluffy. With the mixer still running, add the custard, a tablespoon at a time, beating until all incorporated.

Split into two equal portions and add the vanilla and vanilla powder (plus a pinch of extra salt to taste) to one portion and mix well. Dissolve the coffee granules in the vodka and add to the other portion and mix well.

Enjoy!xxx