I have an odd relationship with cake. That is to say, my feelings towards it have been rather changeable over my lifetime. I expect as a child, I always assumed it was an easy thing to make - the first thing you make, almost equivalent to a batch of biscuits in terms of ease.
Then as I started to bake in earnest in the last year or so, my thoughts changed. Of course I started out with recipes, so I wasn't learning or changing my opinions much in the beginning. But eventually I started taking notice of what was happening in the recipes, and moved on to the pursuit of ratio. For a while I ignored cake altogether, mostly because I was just distracted by other things.
I really came back to cake when I got the book Ratio (more info here). There was a very good section about cake, and it's from there that I decided to start experimenting, and see if I could figure out my own version of the essence of cake. And here I am, and hopefully, here it is.
So, let's get started. First of all, let's think about the ingredients that make a cake. Not the ratio, yet, just the ingredients. This first one that comes to my mind is the eggs. This is partly because my dad is allergic to eggs, and so the quality of 'egginess' or 'non-egginess' has more importance in our household than it might in others. For future reference, it's likely I'll make a bigger deal of the eggy/non-eggy distinction than you might expect in terms of recipe variations and suchlike. So if you notice me doing it, that'll be why. Anyway, I know some cakes don't have eggs in, but we're talking essences here, and as far as I'm concerned, the Essence of cake is a thing with eggs. The other ingredients should also be pretty simple for us to work out. Flour is what makes it a solid food and not some kind of omelette or custard. Fat contributes to the structure and texture, and sugar does too - as well as making it taste nice, which is kind of the whole point.
There we have it, four ingredients to make it cake. Unless you added something drastically different at the same time, taking one of those away would stop it from being cake. Next is the ratio. Yay! And this ratio is so unbelievably simple, you won't believe it. In fact, you might already know it, it's so popular. Ready?
1 flour : 1 fat : 1 sugar : 1 eggs (by weight)
This is where we hit a slight problem. Try not to panic, but we need more than the ratio alone to be certain that what we make will be cake. Because unlike, say, biscuits, cake has a special defining characteristic. Texture. I could make ten batches of biscuits, and they could all have a different texture - fluffy, crispy, soft, crumbly, puffy, chewy, crunchy - and you'd still call all of them biscuits, as long as they were roughly the right shape, size, and flavour. But with cake, everyone's a lot more picky. It has to be light, and airy, and fluffy. If it's not, then it's not cake - even if the ratio is spot on.
How do we make it fluffy? Well! This opens a huge floodgate in terms of new things to learn about, but again, don't panic, because we've learnt about one of them already, and you almost certainly know a bit about all of them anyway. Making something rise (the same as making it fluffy, puffy, airy, light...) is called 'leavening'. There are three main ways to do this. If you want fancy names, there's mechanical leavening, chemical leavening, and biological leavening. Also known as steam, baking powder, and yeast.
Yeast, we've already learnt about, when we learnt about bread, here. Yeast are little living things (fungi), which produce gas, which makes the bread rise. Baking powder is a chemical which produces carbon dioxide when it's mixed with liquid (we will learn more about this in due course). And finally steam. This is what we use when making cakes. When steam heats up, it expands in size. That means if we have tiny bubbles of air inside out mixture before we put it in the oven, they will get bigger, and make the mixture rise. So, the question is just how to get those bubbles in there, and stay there long enough to let the cake rise.
At this point, some of you might be disagreeing with me. A lot of cake recipes actually do use baking powder. And that's perfectly fine. Some recipes say it's 'optional', others say it's necessary. I'll get onto muffins, probably next after cake, and they include baking powder as a more important element. But the spectrum between cake and muffin is pretty blurred, and there are a lot of in betweens. All I'm trying to do here is to show the you extreme end, so you can understand how the spectrum works a bit more. The main point is, you don't need baking powder to make a cake. And I don't like including things I don't need, because it just confuses me.
Getting back to the point. How do we get the bubbles into the cake? This is where our first real decision comes in! There are two main methods we can use here. One of them involves whipping the eggs and sugar to get air into it, and then adding in the other stuff gently (so as not to lose the air bubbles). The other method is to whip the butter with the sugar, to get the bubbles, and then add the other things (gently again, to keep the air). There is actually a different name for each of these two types of cake - the egg whipping method is known as sponge cake, and the butter whipping method is known as pound cake. The two are similar, but also significantly different.
Link to Part 2