Interesting subject for me. I think you are talking about the EC Caddis, generally attributed to Ralph Cutter. I have a similar pattern, developed independently, which I call the Flat Caddis:
I did publish a Roadkill Streamer piece in Rod and Reel, back in '85 or so, that mentioned "funny-looking parachute caddis flies I was anxious to try." I mention that date only because I was once (on another forum) accused of stealing Ralph Cutter's pattern, without giving him proper credit. I think the truth is we both invented it, independently, at about the same time. If you Google EC Caddis you'll see various images.