I used to co-lead a cooking group at church. We were concerned about offering only healthy, whole foods, so my co-leader and I would decide on a menu each month. It would consist of two chicken options, two beef options, two seafood options and two vegetarian options. Each of us would come up with one of each option. We would price our meals out at the local grocery store, then distribute order forms and each member (about 8-10 of us) would decide what we wanted and submit her order and payment. Then one of us would do the grocery shopping for the whole group. We only had about three hours to cook, and sometimes were doing 40+ meals, so we split up a lot of the prep work like slicing meat, cooking rice, chopping vegetables, etc. If something was easy to do all at home, one of our members would do it all at home and bring it up ready to distribute.
It worked really well...we did it every month for almost a full year and it was a great way to have freezer meals on hand without having to do a whole day's worth of cooking. We didn't continue it this year because my co-leader had a baby this summer and I'm pregnant (again), but maybe we'll start it up again next fall.
We learned that there it was easiest to do a planning meeting and decide on menus for about three months at a time as a group. Everyone brought cookbooks and we made a list and copied the recipes. We also met twice a month, once for our cooking session and once for a planning session where we would decide what could be done ahead of time. When we weren't doing prepwork ahead of time, we were starting at 6 and finishing at 10 or 11. With doing the prepwork, we got to where we would start at 6 and be finished by 8 or 9 at the LATEST, so the 30-45 minutes in a planning meeting really made a big difference in our time commitment.