I've got a framework in my /project directory, where I have multiple .sass-cache folders.

For example, I could have this

/project/-/-/one/.sass-cache

And this

/project/-/-/two/.sass-cache

And this

/project/three/.sass-cache

And I want to add all of the to .gitignore. I've tried this:

# Sass #
###########
*.sass-cache*

But it fails and git still picks up changes in them. How do I properly add my .sass-cache folders to my .gitignore file?

With .gitignore, a single asterisk is only a wildcard for a specific directory. If your git version is up-to-date, you should be able to use the double asterisk to indicate any level of subdirectories.

Single asterisk will only match files for that directories depth

foo/*/* == foo/bar/file.xyz
foo/*/* != foo/bar/dir/file.xyz
foo/*/* != foo/file.xyz

Two asterisks matches any directory depth

foo/** == foo/bar/file.xyz
foo/** == foo/bar/dir/file.xyz
foo/** == foo/file.xyz

For your case, I would suggest trying the following...

**/.sass-cache
**/.sass-cache/*

Lastly, I don't know if it would work, but you might also try...

**.sass-cache**

On this last one, I'm not sure how the double-asterisk would get interpreted. The two lines above this should work fine though.