My long quest for shortbread
Shortbread -- made of just flour, sugar and butter -- has a timeless charm. I love it, but didn't really give it that much thought until another cookie recipe came along, a chocolate-pistachio number, that I thought was too sturdy. I wanted something more like a shortbread, crisp but tender.
Then I wondered: How does good shortbread achieve its perfect balance? Did the pistachios in my dough cause the problem? Or the cocoa powder? Or boiling the butter with the brown sugar at the beginning, when it should have just been melted?
I read many recipes, dug into shortbread's history, and baked pans and pans of it.
I learned a lot. For instance, shortbread is associated with the winter holidays because it was made in Scotland in the early days of sun worship to celebrate the new year. The cookie was round to represent the sun, and the edges traditionally were pinched into points to represent the sun's rays. Original shortbread was made with oat flour, a staple of poor people, as was butter, so rich people didn't have the pleasure of shortbread cookies. Because the oldest cookbooks were written for nobility, the earliest written recipes for shortbread didn't appear until Elizabethan times.
In early days in the Shetland and Orkney Islands of Scotland, a round of shortbread used to be broken over a bride's head. (That's one reason to want it to be tender.)
I felt like Goldilocks with the recipes. Too fragile, too sturdy, nothing "just right." For such a simple cookie, shortbread was proving to be awfully complicated.
The first recipe I tried contained cornstarch and confectioners' sugar, and the combination yielded cookies that were like what I grew up calling "melt-aways," not the perfect shortbread the author claimed.
And that brings me to another point: My perfect might not be your perfect. I didn't grow up eating shortbread. I didn't eat any shortbread the day I spent in Scotland 20-odd years ago. My reference points have more to do with Keebler Pecan Sandies than with "authentic" shortbread.
I know, however, that I should be able to carry a shortbread across a room without worrying that it will break.
On I went. I got anxious about how long to mix the butter with the flour. Overmixing is one of the ways to make pie crust tough, because the more you mush flour together with other ingredients, the more the protein in flour turns into gluten. Gluten gives a food structure and chewiness: good for bread, bad for food you want to be flaky or tender.
I called Shirley O. Corriher, a chatty Southerner who is a noted food chemist and cooking teacher and author ("CookWise" and "BakeWise"). First off, I asked her whether the cocoa powder in that original chocolate-pistachio cookie might have been the culprit that caused its tough texture. Not necessarily, she said. The nuts were innocent, as well.
Texture for shortbread cookies has to do with fat and flour, she explained. "When all that butter hits the flour," she said, "it's going to grease the flour so it can't grab on to protein so it can't make gluten."