This is my pattern for the bonnet Princess Charlotte wore home from the hospital. The bonnet was actually put on the baby the wrong way around. It was meant to be worn with the little cables at the back of the head, not the front. My pattern is designed to be worn both ways.
It’s a fairly simple knit with tiny cables at the crown and ties under the chin. I like it in cotton for summer babies and soft wool for cooler weather. Using bigger needles and heavier yarn will yield a bigger bonnet.