There are actually quite a few different versions of this cardigan crochet pattern for free online, but these are a couple of my favourites. You can see my notes below how I made a few modifications.
Free Baby Hexagon Jacket - With ruffles
Hexagon Baby Jacket Free Pattern
I added ribbed cuff sleeves to mine, by alternating between front post and back post double crochet. I also added double crochet edging around the neckline, with increases on the corners of the collar. I finished them off with a lovely handmade button. I can't wait to make more of these for the winter.