Like many young cooks, I started my kitchen endeavours with cake. From the age of about 10, I learned to cream butter and sugar, beat in eggs, fold in flour and milk and put the whole sloppy mixture into the oven, to re-emerge miraculously some time later in cake form. I created numerous variations in shape, size and flavour -- some of them even deliberate!
In some ways, it makes sense to start with cake. Almost all kids like to eat cake, so there is an immediate incentive to learn to cook. Plus simple cake recipes are hard to botch completely: anything with that much butter and sugar in it is probably going to be edible (especially to a proud first-time cook and her parents)! On the other hand, though, making cake remains one of the most complicated exercises in physical chemistry that you are likely to find in a modern home kitchen (the likes of Heston Blumenthal and Modernist Cuisine not generally being home kitchen material).
As a young and impatient cook, I interpreted instructions such as "cream butter and sugar together until fluffy" to mean "mix until you don't see any sugar in the bowl", and as for "beat eggs in a separate bowl and add a little at a time, beating thoroughly until each addition is incorporated", that became "beat eggs, pour into mixture while beating with other hand". The sight of curds of butter-sugar mix floating in a sea of beaten egg was a recurring theme, and actually for a long time was how I thought the mixture was meant to look at that stage. And, you know, my results weren't too bad: they tasted and looked just fine.
So, what's the big deal with adding the egg a little at a time and beating thoroughly, rather than all-at-once and just mixing it in any-old-how? As I understand it, by adding the egg gradually to the butter, you supposedly create an emulsion in which tiny micro-droplets of egg are dispersed in a butter-sugar mixture. When you add the flour, instead of mixing directly with the egg, releasing gluten and potentially becoming tough, and forming large clumps, each bit of flour first becomes coated with the butter, staying tender and forming small delicate crumbs.
The first recipe for which I ever did the creaming-emulsifying thing properly was a lemon syrup cake. Maybe because it had more sugar than usual and hence needed more beating to incorporate the sugar into the butter, resulting in a lighter butter-sugar mix (the point of creaming, in fact) which was then easier to beat the egg into bit by bit; maybe because it was a warm day and that made the butter easier to beat; who knows. In any case, my efforts were rewarded with a lovely smooth-looking batter rather than my usual slightly lumpy mixture, and the cake did indeed have a much finer texture with a small, tender crumb.
And where does chocolate mayonnaise cake come in, then? Well, the method of beating the egg gradually into the butter to create an emulsion is just like mayonnaise (also an emulsion), only the other way round -- to make mayonnaise, you beat eggs and then drizzle in the oil. At some point, a clever cook observed that the basic ingredients of mayonnaise (eggs and fat -- I recommend avoiding the ones with mustard in, for cake-making purposes! Mustard cake? Eww.) were the same as the basic ingredients for cake, and now there are quite a few recipes out there for mayonnaise cakes -- most of them chocolate mayonnaise cakes, maybe because the chocolate helps to conceal any lingering vinegar or other mayonnaisey-non-cakey flavours.
But wait. Emulsions fall into two categories, as I learnt in Year 12 chemistry: O/W (oil in water) and W/O (water in oil). In a cake, you beat eggs (the 'water') component into butter (the 'oil' component), and this results in little drops of egg in a butter sea: a W/O emulsion. But in mayonnaise, you beat the oil into the egg, which results in an O/W emulsion: drops of fat in a sea of egg. This sounds more like my early baking attempts, and moreover would not (I hypothesise) have the same fat-coating-flour effect. So why does chocolate mayonnaise cake work? What's going on here?
Google reveals that surprisingly enough, the differing chemical properties of O/W and W/O emulsions aren't high on the list of 'commonly-discussed topics for food blogs'. It does, however, also reveal that whether a mixture forms an O/W or a W/O emulsion isn't as simple as which component you beat into what: it also depends on the type of emulsifier and how much. So maybe my theory about butter-coated grains of flour is just waaaay off. Or maybe it doesn't matter too much what sort of emulsion it is, as long as the individual bubbles are small enough to produce an overall homogeneous mixture. The other thing that the cake-batter emulsion apparently contains is tiny air bubbles, which are stabilised by the fat particles and presumably help the cake rise as well as give it texture.
Either way, although the lemon syrup cake recipe is very good, my childish baking attempts weren't really that bad either. Maybe the lesson is that cake is never wrong.
(Oh yeah. Chocolate mayonnaise cake? I've never made one. But the internet can't be wrong... can it?)
Lemon Syrup Cake
125g butter, at (preferably warm) room temperature
zest from 2 lemons
1 cup white sugar (caster is good but I've used regular too)
2 eggs, also at room temperature
3/4 cup SR flour
3/4 cup plain flour
1/2 cup milk
juice of 1 lemon
For syrup:
1/4 cup sugar
juice of the other lemon
Cream butter, sugar and lemon zest together until (yup, you guessed it) fluffy. Beat in eggs a little at a time (I crack the egg right into the bowl but only incorporate a little at a time in my beating) to form a smooth emulsion (W/O? O/W? Who cares, it works.) Fold in flour by the 1/2 cup alternately with milk by the 1/4 cup, so that you start and finish with flour. Lightly mix in the lemon juice.
Pour into whatever shape tin you like -- I used to make this as a loaf most of the time, but it also makes fantastic tiny madeleines, and tonight I made cupcakes -- and bake at an appropriate temperature for the right amount of time...
I know, I know, that sounds obtuse. But larger volumes require longer, slower cooking so that the inside has time to cook, whereas small volumes can cook faster and hotter. As a rough guide, I used to bake a loaf cake at 160C fan-forced for about an hour 10 minutes; the cupcakes worked well at 175C equivalent (my current oven cooks quite a bit under-temperature, so I think its 190C is about 175C) for 35 minutes. Test for doneness the usual way, by pressing the top and checking that it springs back and doesn't squidge, by inserting a toothpick or skewer into the middle and checking for raw batter stuck to it when you pull it out (don't worry about making a hole; you're going to do that later anyway), and/or by looking to see if the cake has pulled away from the sides slightly.
While the cake cooks, make the syrup by mixing the lemon juice and sugar and zapping it in the microwave, stirring frequently, until the sugar is dissolved and the mixture looks sticky. When the cake is done, let it cool for a few minutes, then poke holes in it and spoon syrup all over it while still in the tin. Let cool completely, coating a few more times with remaining syrup to get a nice glaze.
I like to put some thin strands of lemon zest into the syrup and then decorate the top of the cake(s) with them.
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