Based a few of my own mods - wider neck opening and wider button band - on these very helpful project notes by Woolen Grace.

Used the 9 month size chart here to actually size the sweater.

Additional Mods:

• Worked button band over 5 sts.
• Switched out the M1 for the kfb to get a more more invisible increase on the yoke.
• I knit the body of the sweater flat, but worked the sleeves in the round. After reaching the spot to set up for the sleeves, I knit those stitches with waste yarn and decreased to get the stitch count of the sleeves. Then I came back, picked out the waste yarn, and put live stitches on the needles to knit the sleeves just like an afterthought heel.

Used the leftover yarn to make the Inseparable Beatrice and Bernard.