Preheat oven to 300 degrees.
Slice both ends off of the Vidalia onions, not much - just enough to where both ends are flat. Remove the skins. On the sprout end (opposite of the root end) - hollow out a ½"-1" deep 'bowl' with a paring knife. Place the onions in a casserole dish, root end down. Pour 2-3 tablespoons inside of each hollowed area in the onions. Pour half the can of chicken broth in the bottom of the casserole dish. Sprinkle with onions with salt & pepper. Cover the dish with aluminum foil.
Bake for 45 minutes. After 45 minutes, raise the heat to 350 degrees and remove the aluminum foil. Bake for another 20-30 minutes, or until the onions are soft & tendere.
Remove from the oven, and slice the onions into quarters. Drizzle the onions with a couple more tablespoons of barbecue sauce, and turn the oven to broil. Place the onions under the broiler for about 3 minutes, then set aside to cool slightly - about 3-5 minutes.
Sprinkle with chopped green onions. You can also sprinkle with with crumbled cooked bacon, if desired, for an extra special touch.