These socks/slippers are done in garter st on 2 needles, with double inc/dec for shaping. They are actually a partial module (hence the name). They are fast and easy to knit.
You will need 2 st markers.

The detailed size given is for women 8, with chart for men size 11, child, and baby (on #6), but it’s easy to adjust to any size, yarn & needles.