Turns out, they're not.
A lot of the reason people tend to assume they're the same, is because in recent years, they've grown to fill more of the same niche. They're essentially both sweet, fluffy, dessert-like baked goods, in little paper cases. The names are more often used interchangeably, and a lot of foods which are named one or the other are actually somewhere on the spectrum in between.
But in actual fact, those muffins are quite a narrow subcategory of what really is 'muffin'-ness. It's actually a type of bread. Most bread is leavened using yeast (learn more here). But muffins are a different kind of bread, because they're leavened using baking powder. That just means, instead of yeast producing tiny bubbles which make the bread puff up, the baking powder does that job instead. Baking powder is just a mixture of chemicals which produce carbon dioxide when you mix them with liquid. Those microscopic bubbles fill with steam in the oven, which is what makes it really puff up in the oven.
So, the difference between bread and cake? Basically, a cake is a sweet thing by necessity. The sugar is part of the structure and definition of the food. But bread is a neutral thing, because the sugar isn't part of what makes it, what it is. So, because a muffin is a type of bread (also known as a 'quick bread'), it is actually a neutral - as opposed to sweet - thing.
It's called a quick bread, because it's bread, but it's quicker to make. The fact it uses chemical leavening (baking powder) as opposed to yeast, means it doesn't need to be left to rise for a total of hours. The baking powder will do it's full job once it's in the oven, so there's no need for waiting around before that. Similarly, it doesn't use mechanical leavening (like a cake), you don't have to spend time whipping up the air into it. Like I said, the baking powder produces the gas as it heats up, and those bubbles expand and then solidify during cooking, so it all happens in the oven.
There are just a few more differences between a quick bread, and a yeast bread. Although quick breads aren't necessarily sweet things, they are still a lot richer than plain yeast breads. That's because they also contain eggs, fat, and generally milk as the liquid, instead of water. All of those things make them more rich and flavourful, an generally a bit more cakey.
Quick breads is a category that also contains things like 'banana bread' - it's not a yeast bread. So you could make a quick bread batter, and then cook it in a loaf tin, or in paper cases, and that's the only thing that would define whether it was a 'bread' or a muffin. The mixture and the ingredients are exactly the same.
By now you should be ready, there's only one thing left to say... Ladies and gentlemen, the quick
2 flour : 2 liquid : 1 egg : 1 butter (: 1 sugar)
The sugar part is just there because muffins are very often sweet, so if they are, that is the amount of sugar you should use according to the ratio. Also, please remember that the egg is measured by weight, but you can assume that one egg weighs about 50g. So if you used 200g of flour, use two eggs. I didn't include the baking powder, because it's such a tiny amount, and it's easiest to measure it by volume rather than weight. So here is an independent, flour-to-baking powder ratio:
100g flour : 1tsp baking powder
It's pretty simple really. And the method is extremely easy.
- Bake things at 180C. I know I said 175C when I was talking about cakes in the last post, but really, it doesn't matter much at all. Unless a temperature is drastically different, somewhere between 175 and 185 is going to be fine. Ovens really aren't that accurate anyway. So preheat the oven to, something.
- Melt the butter, in the microwave or on the hob. Let it cool down a little bit - you don't want it to be so hot it cooks the eggs when you mix it in. Trust me, it is not pretty. When it's about skin temperature (don't be too perfect about it, just use your common sense - is it hot enough to cook eggs?), put it in a bowl with the eggs and the liquid. In almost all cases, I'd use milk. In fact, I can't yet think of any cases when I wouldn't use milk, so use milk. Beat them together with a whisk until they're combined. Beat just means, stir quickly, using a whisk.
- Now you add the other (dry) ingredients. Most recipes have you mix the dry ingredients together in a separate bowl. I still fail to understand what benefit that actually gives, except having an extra bowl to wash. Flour and sugar will mix together just easily by going together in liquid at the same time, as if you mixed them separately and then added them. So I don't bother with that step. If anyone can give me a real reason why it's better to combine the dry ingredients first, please feel free, I only omit it because I can't think of a reason to do it.
- So, sift the flour in, and add the sugar and the baking powder too. Beat the mixture until it's just about fully combined. It doesn't matter if there are some lumps, as long as you're not still turning over dry flour, it's mixed enough. If you mix it too much, they can become tough. This is because the flour will start forming gluten (remember, kneading is what forms the gluten in yeast bread, but we don't want that to happen with muffins). So just about combine everything, and then you're good to do. Pour it into a tin or muffin cases or whatever you fancy, and stick it in the oven. They'll take somewhere around 30 minutes in muffin cases, longer in a loaf tin. It's done when you can do the usual toothpick trick - stick it right into the centre and if it comes out clean (as opposed to sticky or covered in crumbs), then it's done.
And we're done. Muffins, disperse!