I found a pattern on Ravelry called Astrid by Delusional Knitter Designs. It's not free, but it's definitely worth the few dollars I paid for it. It's a great pattern and I've already used it again! In this case, I changed it slightly to suit what I wanted. I cast on 232, which is a bit less than what the pattern calls for, but I didn't want it quite as big around. I also removed a few rows as I didn't want it as wide as what the pattern called for either.
I'm thrilled with how this cowl turned out. I look forward to wearing it regularly when it's chilly again!