I made myself a poncho like this last year when I was anticpating hand surgery. I wore it to church one Sunday not too long ago and my 9 year old granddaughter put it on. She wanted one so Nana obliged today.
I used to have a pattern like this but no longer have it. I just cut a rectangle from the fleece. I left the fabric with the fold to where the right arm will be. I serged the edges and sewed a shoulder seam leaving a neck opening of about 20 inches circumference. I sewed a "dart" at the neck edge for the right shouler to take out a little of the fullness at the neck. I turned up a bout a 3/4 inch hem and stitched. This was a quick project taking only about 1/2 hour to make.
My poncho is monogrammed on the left chest but I decided it might not be a good idea to monogram one for a child. It might be difficult for her to keep the monogram in the right place when she wears it.
This is made using the plush fleece. I hope she likes it.