First, reader Glenn, let me just say that I’m still baffled as to why it’s called the “one bowl” method since I’ve never succeeded in using less than two bowls for a one-bowl cake. So right there I’m a little down on it. But there’s no denying that one-bowl layer cakes are very moist and tender devices, I dare say more so than cakes made via any other method. But why is that?
It all has to do with the manner in which the fat is introduced to the batter. A cake mixed via the creaming method — which is the standard for most layer cakes — starts out as a well-beaten mixture of fat and sugar. Doses of dry and wet ingredients are added alternately until all is combined and ready to bake. With the one-bowl method all the dry ingredients including the sugar and mixed together first, then the fat is added before any liquid touches the mixture.
The effect of combing the flour with the fat before the liquid is to effectively grease the flour granules, which prevents the gluten molecules they contain from bonding with one another, even after the water goes in. It’s a pretty neat trick and a very effective way to undermine a gluten structure. In fact it’s so effective that you have to go out of your way to beat the heck out of the batter in the final steps to ensure that at least a few of those protein molecules find one another. Otherwise the cake layer wouldn’t be able to stand up. So you see why one-bowl layers are so tender, no?
The one-bowl method is not without its detractors. Many people find the relative density and fall-apart tenderness of one-bowl cakes off-putting, especially people who’ve grown up eating bakery cakes, which are generally made via the creaming method and as a result have a lighter crumb. Bakers who like to make very tall or elaborately carved novelty cakes also tend not to like one-bowl cake layers for reasons that should be obvious. One-bowl layers make poor building materials. But for a buttery, melt-in-the-mouth eating experience there’s no question that a one-bowl method cake can’t be beat.