see that hole? that's tunneling. no bueno
Gluten. It's our baking friend. But she's a high maintenance chum. If you ignore her, let her mingle with your sugars and fat unsupervised, she'll throw a tantrum in the way of gaping bubbles of ire. Treat her right, with delicacy and respect, she'll give you a glorious crumb that's compact yet delicate.
I got to thinking about tunneling when someone mentioned not making Golden Eggs because they didn't have the right flour. I like this attention to detail, someone taking the floured arts seriously enough to forestall a cake binge. I, however, would not have been so stalwart. In the throes of a carb crave, I'd have taken my chances with the wrong flour. Because while some people believe that to make a cake you must use cake flour, I'm all for the AP when no other is to be had. I have one caveat, you must add the flour until JUST combined and no more. As a matter of fact, if you want perfection, don't use the mixer for the flour addition. Instead, sift the flour directly over the bowl and fold gently into the batter.
the golden egg, uncracked
Here's the deal, different flours have different percentages of gluten, from cake flour with the lowest to bread flours with the highest. But even though most brands offer a cake, an AP and a bread flour, the average flour mills won't guarantee consistent gluten percentages, they just aim for a range and call it a day. I'm not going to name any names but they are the usual grocery suspects. When I hear the baker's lament, "I did everything exactly the same as I always do but it all went to hell," I immediately ask "What kind of flour do you use?" because you could have mixed exactly as you did the last time you made that cake perfectly but this time it came out rubbery and full of holes. Chances are, the gluten levels in the new bag of flour you just bought are higher.
But say you have a consistent flour, King Arthur for example, and you manage to tunnel the hell out of a cake, producing gargantuan gaps and rubber texture. Here's what almost certainly happened: you overmixed the flour addition to the point that gluten overdevelops and traps air pockets in the batter. The cake, for obvious reasons, will rise higher because you've just given the gluten proteins permission to trap air willy nilly. A proper flour integration will give you moist, delicate and dense crumb. Even when you use AP instead of cake flour.
the golden egg, cracked open but not tunneled
This particular conundrum is a cake thing. Breads require elevated gluten development for proper texture and goodness. And there are a few recipes where I'd never use AP, Angel Food Cake comes to mind. But that's why I love baking, there's a magic to how and why you combine ingredients and for how long. And once you know the rules, you can find a way to break them to cater to your ravenous cravings at a moment's notice.
I may be slightly biased, since they're my neighbor and I teach there now and again, but I never use anything but King Arthur Flour. They are the only national mill that I know of that guarantees a specific gluten percentage in each bag of flour. The lovely Susan MIller at King Arthur Flour gave me the breakdown of their flour's gluten content for your edification:
All-purpose: 11.7% protein
Bread Flour: 12.7% protein
Whole Wheat: 14% protein
Sir Lancelot Hi-Gluten: 14.2% protein
Pastry: 8% protein
Cake: 7% protein
Pretty amazing, right? So next time you add flour to your batter, pay utmost respect to our friend gluten.