Beat in the flavoring, then with a flat wire whip, called a "sensible egg whip," fold in the flour and nuts carefully and with as few strokes as possible, not sifting all the flour onto the batter at once, but adding on a little flour and nuts and folding it in with two or three strokes, then adding on a little more flour and nuts, and folding again.
Continue till all the flour and nuts are folded in, but do not fold any longer than is necessary to mix in the flour.