Here are the basics:
Yarn: Cascade 220
Needles: size 8 USA
Cast on 80 st. k1 p1 ribbing for about an inch and a half. Spiral purling every 10th stitch for about 20 rows or until ready to decrease. Decrease while keeping the spiral purling as much as possible... Perhaps someday, I'll be organized enough to write out the pattern, though I'm sure similar and more refined patterns abound.
I am happy with the outcome and have told my MIL that if Amy likes it, I'll make her a matching scarf for Christmas.