This soda bread gets nutty flavor and hearty texture from a combination of whole-wheat flour and wheat bran, but also includes some all-purpose flour for structure. The dough comes together in a single bowl and without a mixer. Even the butter and buttermilk are used cold so there’s no need plan ahead. Baking in a cast-iron skillet develops a nice bottom crust, but a parchment-lined baking sheet works almost as well. (If using a baking sheet, you will need only 1 tablespoon melted butter to brush on the loaf after baking.) The bread is best the day it is baked, but leftovers will keep in an airtight container for up to three days. Slice and toast before serving.