Very, very simple really. Here’s sort of the “pattern”, although all parts can be highly modified for size and shape!

YARN

Aran weight yarn.
I used Sublime Cashmere Merino Silk Aran, 75% merino, 20% silk and 5% cashmere. It’s super soft and squooshy, and tightly spun with lots of plies. I used four balls, 94 yards each.

Needles

6.5 mm (US 10.5) needles

Stitch pattern is “stockinette lace ladder” from Barbara Walker’s A Treasury of Knitting Patterns (Vol. 1, otherwise known as the blue one). Multiple of 4 sts.

Row 1 (RS): * ssk, yo twice, k2tog *, repeat from * to * across
Row 2: *p1, (p1, k1 into double yo), p1 *, repeat from * to * across.

PATTERN

I wanted the sleeve to be quite fitted all the way up, so I began by casting on 32 stitches and doing 4 rows of garter stitch, on 6.5 mm needles.

Row 1 (RS): k2, pattern across 28 sts, k2.
Row 2 (WS): p2, pattern across 28 sts, p2.

Work even for about 12″.

Increase each end every 4 rows until you have enough stitches to add another ssk, double yo, k2tog at each end, with one knit selvage stitch.

Work even for another 5″ or so, then do another set of increases. This is the widest point.

Work even until the piece goes across your back – I sewed up the first sleeve so I could make sure to have the correct starting point for the back, and just tried it on periodically to check the size, stretching slightly.

My “back hole” is about 19″ – this isn’t a cross back measurement, as it needs to go around the top part of the shoulder as well. When it’s long enough, make another sleeve, mirroring the placement of the sleeve decreases and ending with four rows of garter stitch. Weave in the ends and go!