I have made this hat in Tunisian crochet using hook size 5mm, and Dk weight yarn. This is my first one with round. The technique called magic loop. It is my own pattern, and I have shaped the crown as I shaped the crown of knitted hat. I have made the edge using crochet front and back post stitches.
close look at shape part
close look at the top of hat
more pictures as workshop
close look at the join part
Here is the link to a video of how to make a magic loop