Made a couple of soup bowl cozies for a quick gift the other day.
Two fat quarters or two 10 " x 20 " pieces of fabric and four pieces of batting 10 " x 10" and thread is all you need to make these. The full instructions are on this blog post.
The photos below are all soup bowl cozies I have made in the past.
I generally make them in pairs as they are reversible. The can be put in the microwave and are fully washable. I don't throw them in the dryer though.