Flycutter would be the way to do this if you don't have a router.
Drill your hole in the blank, then replace the drill bit in the
flycutter with a piece of steel rod so the hole doesn't get wallowed
out. I'd sandwich the blank between two scraps of wood for holding it.
Do it in a hefty drill press or a mill. One sort of off-the-shelf
flycutter looks like this:
http://www.generaltools.com/product....52&sectionid=2

More like a trepanning tool. Run very slowly. They've got these
fairly cheap at the local hardware store, I don't know what you'd have
available where you are. I've got a couple of these in different
sizes, they work well if you've got a heavy enough machine.

A small router in a router table would be the way to go, since you've
got the hole. Use that as a pivot and just rotate it against the
cutter until done.

I've also done small plastic disks by roughly cutting them into a
circular shape, sandwiching them between two chunks of door skin on a
bolt, then putting that in an electric drill and using a wood rasp to
smooth things up and reduce it to final diameter. Polish with sand
paper. Could do the same on a drill press, just make sure the bolt
doesn't walk and the chuck doesn't drop.

Another method would be to do as above, stick a sanding drum in the
drill press, clamp something for a pivot pin in place on the table and
then spin the blank on the pivot against the sanding drum.

I wouldn't try to lathe turn it at all.

Just number of different options.

Stan