The Food Lab: Better Home Cooking Through Science

ingredients lists, and they’re nearly identical: flour, butter,
baking powder, baking soda, and liquid dairy. But one ends
up fluffy, tender, and relatively flat, and the other ends up
tall, flaky, and crisp. The difference is all in the details.
First off, biscuits are a dough, not a batter, which means
that the ratio of flour to liquid is high enough that it can pull
everything together into a cohesive ball that’s soft but
doesn’t flow. Even more important is the way in which the
butter is incorporated. With pancakes, the butter is melted
and whisked into the batter, resulting in a sort of uniform
tenderness. For great flaky biscuits, on the other hand, the
butter is added cold and hard, and it’s added before the
liquid is. As you work the hard butter into the flour, you end
up with a mealy mix comprised of small bits of butter coated
in flour, some amount of a flour-and-butter paste, and some
completely dry flour. Now add your liquid to this mix, and
what happens? Well, the dry flour immediately begins to
absorb water, forming gluten. Meanwhile, the flour
suspended in the flour-butter paste doesn’t absorb any water
at all, and, of course, you’ve still got your clumps of 100-
percent pure butter.
Kneading the dough will cause the small pockets of
gluten to gradually link together into larger and larger
networks. All the while, butter-coated flour and pure butter
are suspended within these networks. As you roll the dough
out, everything gets flattened and elongated. The gluten
networks end up stretched into thin layers separated by
butter and butter-coated flour.
Finally, as the biscuits bake, a couple things occur. First,
the butter melts, lubricating the spaces between the thin