I came across this the other day. It's a generic mitten pattern you can do with any size needle, any yarn. It's based on your gauge and your own measurements. I'm currently knitting a pair based on this and it's going quite well. The only thing I would caution is to add about four extra stitches if you're doing the Fair Isle type that she has pictured. The Fair Isle pulls the work in a little and will make the mittens snug. So far, I'm finding they're a good fit. One thing I never thought of was my odd size hands. I have small wrists and wide hands. I had to increase a few stitches after the cuff to accommodate this, but it's working well. This is the first mitten pattern I've done that actually fits.
If you're knitting mittens for someone else, have them trace around their hands on a piece of paper. Just in case they're not around or are at work or school. Little kids don't like it when you constantly chase them around the room with a measuring tape.