This is the method I use for all buttonholes except the very tiny, where some form of eyelet is more appropriate. It looks great on garter stitch bands like the ones on wee Chickadee.
This tutorial is an extract from my book Little Red in the City which also includes tutorials on cast ons, short rows, swatching and lot of other information to help you make great fitting garments.
There are a few variations — in Knitter’s Almanac Elizabeth Zimmermann writes:
“I had heard of one-row buttonholes from all directions; you make it all in one row, they said, and don’t have to worry about it on the next row or the row after. Worry? It’s a pleasure to spend three rows on a buttonhole. If you are involved in a technical manoeuver, it makes the knitting go like the wind.”
Personally I prefer one row buttonholes not because it gets the buttonhole over with but because I find them neater and less prone to stretching out of shape than any multi-row buttonhole I’ve ever done. I can’t say I find turning the work irritating, but if you do you’re in most excellent company, the above passage is from the July chapter of the almanac where, on a park bench in Blegium, she spent time developing a one-row buttonhole without the turning. Elizabeth titled the result the “Definitive (I think) Buttonhole.” I love the implication that there’s always a possibility for improvement. Try both of these, but maybe you can come up with an even better option.
This version begins in almost the same way as the one above except that the first stitch is slipped and then the yarn is brought to the front. The stitches are bound off as above and then the remaining stitch on the right needle is slipped to the left, twisted. Remove the last stitch on the right needle and place it back on the same needle twisted, bring the yarn to the back over the right needle and pass this stitch over it. Firmly backwards loop cast on the total number of buttonhole stitches onto right needle. Knit the next 2 sts on left needle tog.
No matter how tightly you work it the backwards loop cast on is a bit softer than a cabled cast on. It might be more appropriate for lighter-weight projects or smaller buttonholes — I find the version with the cabled cast on can end up a bit too tight on buttonholes worked over 3 to 4 stitches but otherwise I generally prefer the firmer version despite the need to turn the work. I like to think arguing is implied in the encouragement to be a “thinking knitter”.