Yarn: Bernat Waverley, worsted weight 
You have no idea how hard it is to find or make a good mitten pattern. Or, maybe you do. This pattern is amazing, and I will be making more mittens from it in the future.
This pattern is pretty easy, but it does take a bit of concentration. Don't expect to be able to pay attention to a movie for about the first 20 minutes, or so.
Crochet this project very loosely, unless you want to spend the majority of your time trying to squeeze your hook into the backs of slip stitches. (And, there a lot of slip stitches!)
Repeat R5-8 2x extra before sewing the sides together.
I used the "easy" thumb method, but chained 16 instead of 13. You know, 'cause of my long thumbs.
I'm really hoping the thumb stretches enough to comfortably fit a fleece liner inside the entire mitten...
You could probably make the thumb hole maybe 2-4 chains wider when working that row if you are planning to line them. I wasn't sure how the thumb would work out, so I only widened the cuff/main part of the mitten.
For the left mitten, add the "Repeat R5-8 2x" before making the thumb hole row.
Do not use "Repeat R5-8 2x" for either mitten, if you're not planning on lining the mittens.
I'll keep you posted if/when I line the adorable mittens.
Ps - I'm super pumped to finally have these finished. The text in this post was save as a draft for two months. The second thumb piece was made, but I procrastinated actually attaching it, until today!