Made these little slippers last year. Very quick project. My daughter didn’t have a chance to wear them - her footsies grew up too fast. I am going to make more.
Here is a link to pattern on Etsy.

For non-slip backing I used Saf-T-Back, rubber compound for rug backings.
I got it at the local craft store.
JoAnn on-line carries it too.

P.S.Once again, I wish the pattern was charted.

Added: I charted the pattern and added one extra row at the base to make shoes deeper.
Much easier to work with!
…and I made more Mary Janes!