I did not have a size 11 circular needle to start on, so I used my 10 1/2. After casting on and knitting the first row, transferred it to size 11 DPDs
The hat was extremely easy to make, you could really finish it in one day.
It is nice and cozy, but ultimately ended up being a little big for me - it keeps sliding down on my head and covers my eyes sometimes. Next I would either use a smaller needle to knit the part above the ribbing, or decrease the number of stitches.