Anyone know of a tried and true cocoon dress pattern?

Hi everyone! This is my first post to the forum. I have purchased some amazing linen which I plan to dye and would like to recreate a Rachel Craven cocoon dress. I'm having the hardest time finding a similar pattern. It doesn't look like a difficult style of dress to make, so I'm wondering if people just make their own patterns when they want to create a cocoon dress? If anyone knows of a place to start, I'd love the help!