I think it is your call. The flannel makes a heavier quilt so leaving out batting is probably okay. If you don't want the thickness of batting, I think I'd put an extra layer of flannel inside for batting if it were me. I think you need some body when you quilt it. Just my 2cents.

What is the climate for the recipient? If it's the warmer Southern states or SoCal, I'd say you don't *have* to put in a batting. You could tie or do a decorative machine stitch to tie the top and bottom together and call it a summer blanket. But if you want to machine quilt this project, then you might want a thin batt or flannel in the middle as toolgranny mentioned - add my 2cents worth to hers.

Teresa

And don't forget to prewash the flannel!
Three cents!
Theresa

Here's another 2 cents' worth. I almost made the mistake of omitting batting when I had a top with a lot of white in it and a darker backing. In order to hide the seam allowances and get the white to "pop," you need a light-colored batting. This is especially true if you are using thinner fabrics for the top.

Thanks everyone. I think I'm going put flannel in the middle. I'll post a picture when it's done.
Darlene