Cut the butter into tablespoon-sized pats, cut each pat into 4 cubes, and freeze until hard, 20 to 30 minutes. Pulse the dry ingredients in a food processor fitted with the steel blade to mix thoroughly. Add the frozen butter cubes. For scones or for biscuits with a flaky, layered structure, pulse just until the largest butter pieces are the size of peas and the smallest resemble breadcrumbs. For classic fluffy biscuits, continue to pulse until all of the butter pieces resemble breadcrumbs. Add the wet ingredient(s) and pulse just until the dough comes together as one mass, not longer. Do not allow the butter to melt or form a blended paste with the flour. Turn out the dough onto a lightly floured board and knead a few times. Shape as directed.
