A sculptured perfect tower of golden textured cake, dripping with strawberry conserve and oozing cream through the centre of two soft layers sandwiched together. A fleck or two of icing sugar and the cake is inviting prey for any vigorous cake slicer.
Personally, I can’t think of a classic sponge without thinking about the repetitious task of baking and photocopying, slice after slice of cake to count the tiny holes per cubic centimetre. All this to determine gluten structure and find a quantitative answer to why. These days my tests are more subjective – I just want to cook a great sponge cake every time.
For the purpose of this exercise I wanted to delve into this classic recipe, its history and lineage in an attempt to answer some very common questions. When you Google ‘sponge cake’, at least 5,720,000 entries show up. Immediately it proves to me that this cake is a common culinary occurence across many ovens in the world – just called different names..
However after a quick perusal, it seemed more natural to turn to the masters for classic instruction in making great sponge cakes. Name dropping, references included Anne Willan, Prue Leith, Julia Child, Irma Rombacher, Nigella Lawson, and even Modern classics with Donna Hay. Plus a fair few patisserie books I could find all gave me differing cake recipes to compare. After deciphering methods and ingredients proportions, I feel now I have more insight into the intrinsic sponge, its evolvement and what I need to do to make a perfect one.
All about a sponge cake
The sponge cake has many guises, but its main attributes are the aerated texture, soft springy crumb and the whisking technique by which it is made. It is sweet, and puffy, with not a lot of taste of the fat, an all the colour and flavour coming from bright fresh eggs. It is the first cake that any patisserie student is set to master. It is a cake that performs the basic science of aeration, protein and gluten in cooking. Baking this cake is real molecular gastronomy.
There are two types of sponge cake from which we refer to with the same name and within that there are many versions of technique to get to the perfect results.
One type comes from the Genoise or Genoese sponge, made traditionally with only four ingredients – eggs, sugar, flour and butter. This recipe is truly a French creation. A young patisserie chef by the name of Fauvel first claimed he invented the sponge in the nineteenth century. He named it Pain de Genes, and after victory at a particular battle that Genoa was waging against Massena. In this time period most cakes were made as a feast for a festival, tradition or sacrifice.
Traditionally in a Genoese sponge the whole eggs are whisked together over a gentle heat with the sugar to create a foam and ribbon effect when spoonfuls of batter are pulled from the mixture. If these ribbons hold for more than 10 seconds on the top of the batter, you are half way there to creating a cooked cake with a soft, springy texture.
Each of the four ingredients supply essential building blocks to the structure of the cake, even though originally fat was not added to this whisked cake, and the crumb was built from sugar, egg protein and flour alone.
With the simplest of ingredients we would imagine that it would be even simple to put together. The basic principles is to get as much air as possible trapped in the mix of egg and sugar through a very vigorous and heated whisking process. The sugar crystals should dissolve in the wet egg, the light mixing of dusty flour to provide a base and fat to make the whole cake mould together. Simple yes – just needs patience.
The more traditional, time-honoured recipe, that Julia Childs would choose is the formation of the egg foam, while hand whisking over a simmering heat. Exhausting, trust me. It takes a dry afternoon and considerable concentration. A Perfect slow food companion. With the advent of electricity the more conventional method has been the cake mixer, or even electric hand beater. Both give us back time and take away the need to use heat as a creator of aeration.
The second type of sponge comes from another technique for mixing the eggs. The eggs are separated, and whisking whites until stiff, and adding the sugar to either the egg yolks or to the egg whites to dissolve. In earlier times it was commonly made with half potato starch and half wheat flour giving a variation called the Savoy sponge. A cake made with separated eggs tends to be more firm than the Genoese sponge and the butter added means that this cake will stay moist for at least 2-3 days longer than a Genoese Sponge.
This cake is similar in composition to the Victoria sponge that was baked for the Monarch Queen Victoria in her honour. The Victorian sponge made its place with ladies sipping tea in larger than life frocks and more powder on their faces than a top of the sponge. And the recipe has made it to the pages of many a cake book, dressed up with layers of cream, rolled with a filling or even baked in sheets to be shredded for a trifle.
Over time stabilising of the sponge has taken place to help with sinking cakes and unnecessary drying out of the crumb. Cornflour, baking powder or self raising flour for the quick fix can all be added. All additives with the agenda of creating consistent cakes. The truth is they may provide puff – but not necessarily profit the flavour profile.
Adorning the batter with flavourings such as chocolate, vanilla, coconut, coffee, fruit pulp, and ground nuts all take a little away from the lightness of cake but are limitless in the way this cake can be presented. When this recipe reached its peak in the days of high tea Biscuit aux amnades – or the almond sandwich cake was the traditional topping.
It is my belief, that good technique will get you through when prepping any version of this cake. Modern cooks stay true to the principles of this cake because it is the old fashioned tips that work well. Accuracy of measurements will always create better cakes.
However, even a baker making a sponge every day, still has to face trickery with Mother Nature to conquer the perfect sponge cake. High humidity in the air, differing altitudes and even cold rainy weather can change the outcome of a sponge cake.
The science in sponge cakes
Any cake is essentially a ‘web’ of eggs, flour, sugar and butter. The tender texture comes from gas bubbles that are created in the mixing process. The eggs provide all the moisture and some of the protein which supplement the gluten structure of the cake. Heat or intense whisking coagulates this protein in eggs, enabling them to trap and hold large quantities of air and thus increase quickly in volume. Sugar on the other hand, works three ways to bring air into the mixture, plus can work to sweeten the mixture as well as dilutes the flour proteins to limit the development of strong gluten bonds. Flour provides the “glue” that holds the proteins together to form the set cake.
In a sponge cake the amount of flour and mixing time is limited to purposefully under utilise the strong gelatinous network that any starch provides. The addition of fats like butter or shortening gives tenderness to the cake, but in earlier recipes fat wasn’t crucial to the production.
When baking powder or other raising agents are mixed in, the heat in the cooking process mixes the alkali and acid parts of the powder together to create carbon dioxide upon heating. This in turn creates gas bubbles which cause a softer, springy texture to the cake. The addition of cornflour or another strong starch such as potato starch can be used to even further refine the texture of the crumb, and can reduce cooking time to produce a moister cake. Adding cocoa solids will absorb water in a similar way to flour takes moisture from the eggs.
To test the differences in sponge cakes, the best way was simply to make every single version. With only two trays of eggs I decided that five different cakes would be a better starting point. The first one was made in the traditional method of hand whisking the whole eggs; the second method a classic Genoise type sponge but using a cake mixer; the third by separating the eggs before whisking, the fourth by making a cake with only egg yolks, and a fifth cake by adding cornflour and baking powder.
The cakes were then tasted and dissected by a small focus group of people (16 members) and asked to rate the order of like and why. The results were conclusive if not very scientific.
Out of the 16 people who surveyed the five cakes, 60% preference went to the sponge cake made using a traditional whole egg recipe but using a cake mixer. Tenderness of the crumb and overall texture and height was given as the reason for their preference. The remaining 40% preferred the cornflour and baking powder cake. The fluffy, yet firm texture was the given as the reason and also comment was given that everyone thought the cake was sweeter.
My only conclusion from my informal experiment was that the chemicals can help with stability, yet it is only technological advances that can improve on a classic.
Note: Equipment I used when cooking my sponges included a trusty Kenwood mixer, with whisk attachment. Metal 20cm round sandwich tins (Purchased from local supermarket) and a Fisher and Paykel oven on the middle shelf. All eggs were no. 7 free range and all sugar is white caster.
Making a Classic sponge cake
Assemble all the ingredients before you begin. Get the eggs ready, flour and sugar measured, tin prepared, oven turned on, and butter to room temperature before you do anything else.
Choose a good cake mixer with a whisk attachment. A hand beater is good but, bear in mind the eggs need vigorous whisking for a good 10 minutes. A balloon whisk is valiant, but personal strength and stamina are needed too.
The tins need to be of an even size, and not too different to what is stated in the recipe. A tin, which is too big, will inflate the inner cake, but as it cools will deflate easier. If the metal is too thick, the cake won’t cook evenly and likely to sink. Metal as opposed to silicon will give better colouring on the outer crust.
Always line the tin with baking paper. A good method is to grease the inside of the dry tin with a little butter. Brush it on with a pastry brush or smear on with a piece of greaseproof paper. Cut a circle of baking paper to fit the bottom of each tin. Cut rectangular strips to fit around the sides of the cake tin. Grease the inside pieces of paper then dust with a little flour or cornflour. Shake off any excess.
The eggs are the key ingredient. They must be at room temperature but a tip for bringing them back to temp if they have been chilled is to place them in tepid water for a few minutes.
Beat the eggs well goes without saying. Everything will go better if the eggs are whipped well from the get go. It takes a 8 to 10 minutes, to fully dissolve the sugar, and give the foam enough puff. Take the time to get that right. And of course, use a clean dry bowl to begin with.
The sugar is almost always caster. It is finer in texture, with smaller crystals, therefore giving more surface area to cut through the egg and fat while mixing.
Without flour the sponge becomes a soufflé. As a general rule to help navigate the variety of recipes for sponge cake, the weight of the flour is equal to the weight of the sugar, and roughly half the weight of the eggs. Sifting the flour is key. The more it is sifted the finer the particles of flour. The process of sifting onto waxed paper allows the flour to stay well aerated and almost dusty, therefore disappearing into the moist batter as it is tipped in.
No matter how delicately you fold in the flour the eggs will deflate. Just remember less is best, so fold flour carefully with a metal spoon, and as soon as the last speck of flour has disappeared don’t mix any further.
The butter is interesting, because a good reason to like this cake is that it has less butter than other denser cakes, yet it is still important to the moistness and structure. But it can be left out if necessary. Something to consider with ever-rising dairy costs. Methods can differ as to how to combine the butter with the egg batter. One way is to mix a small portion of the cake batter with the butter then fold this back into the main mix. Another is to pour the melted butter into a bowl then pour the mixture on top and fold in from the sides. It very rarely helps to substitute with other manufactured fats or spreads.
Cooking the cake
It is important to get the cake batter in the tin and into the pre heated oven as quickly as possible. This means not leaving the tin sitting on the bench while waiting for the oven to heat, or waiting for something else to finish cooking. The longer it sits the more likely it is to flatten.
Cakes will sink if they have not been baked for long enough, so follow the time stated in the recipe, use a timer, and don’t be tempted to open the oven door during cooking. If the oven is too hot the cake will rise quickly and then sink. If the oven temperature is too low the cake tends to cook unevenly and eventually peak in the middle.
The final cake
The cakes are ready when they are firm in the centre and should spring back when touched with your finger. Another sign is they have slightly shrunken away from the sides of the tin. Refrain from sticking a skewer into this cake, as it will leave big holes and sink the middle of the cake. A lot more intuition is needed.
It pays to take the cake out of the tin after only about 5-10 minutes resting time. The bottom of the cake can go soggy if left in the tin too long or if left on a solid surface too cool and not a wire rack.
Without a doubt, a sponge cake is best eaten the day they it is made. Cover the fresh cake with a dry tea towel until ready to fill and serve.
If it has to be stored the cake can be covered with plastic wrap and stored in a cool dry place. Bear in mind the gluten changes quickly with a dehydrating cake, and can cause a stale and flavourless cake.
The cake can be frozen in plastic bags, however the texture of a frozen sponge can be compromised over time. They are best wrapped and frozen stored for short weeks and often limited to curing in rum for festive puddings.
For a perfect sponge cake
Preparation time: 15 minutes
Cook time: 25 minutes
175g plain flour
175g caster sugar
75g butter, melted
Preheat the oven to 180°C / 350°F on conventional bake.
Grease and line two 20cm round shallow sandwich tins with baking paper. Grease paper with a little more butter and sprinkle with a little flour or cornflour. Shake off excess.
Sift the flour three times with the final time onto a piece of waxed kitchen paper. Set aside.
Place the whole eggs and sugar in the bowl of an electric cake mixer with the whisk attachment.
Beat for 8-10 minutes or until thick and pale and tripled in volume and all the sugar crystals have dissolved. You can feel the crystals of sugar in the egg white with your fingers if they haven’t.
Take the bowl off the cake mixer and sift the flour into the mixture, folding gently as you go. Once all the flour has disappeared, take a spoonful of batter out and mix it with the melted butter. Gently fold this portion back through the bowl of batter.
Divide the mixture between cake tins. Make as even as possible. Tap the tin lightly on the bench top to remove any air pockets.
Place immediately into the oven and bake for 20-25 minutes or until the cakes are springy to touch and come away from the sides of the tins.
Allow to cool, for 5-10 minutes in the tin then turn onto wire racks. Remove the baking paper.
When cool, spread with strawberry jam, whipped cream, and top with fresh strawberries. Sandwich the two layers together and the sprinkle whole cake with a little icing sugar to serve.
Try this gorgeous chocolate gluten free sponge recipe with chocolate filling and raspberries
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