Trim beets, leaving about 1 inch of stems attached. Wrap beets tightly in double layers of foil to make 3 packages and roast until tender, about 1 hour.
When beets are cool enough to handle, slip off skins and stems and cut each beet into about 6 wedges. Beets may be prepared up to this point 1 day ahead and chilled, covered. Transfer beets to a baking dish and cover with foil. Reduce temperature to 375°F. and reheat beets until heated through, about 20 minutes.
While beets are reheating, put parsley in a small bowl and with kitchen shears very coarsely snip.
Toss beets with butter, parsley, and salt and pepper to taste.
