I saw Courtney's Batman cape just a little bit ago! I stored it away remembering she used the Cozy Winter Hood from the O + S Little Things to Sew book. She made pointy batman ears. I copied all of that. Except I think I used velcro across the front on the cape part to keep it closed and didn't use a tie under the chin. And stripey black and gray jersey for the lining which is yet again my Old Navy clearance sweatshirts that were $1.47 each.
Since it was a play cape, I really just gathered and stuffed the center section of the cape in the hood opening at the nape and sewed. I used pinking shears on the edges to cut around the yard or so of fabric that drapes down as the cape, so I wouldn't have to hem. My only change would be to interface the pointy ears, so that they stick up better. I just didn't have any on hand. It would have been a good thing to do!
And I'm so glad that I didn't actually make this for my OWN child, because this is how it went down...

He's never liked things on his head. Even if you get to be batman...
So always remember to be yourself, unless you can be batman... always be BATMAN!!!
Or whatever superhero you want to be... those work, too!