• Make the cornbread stuffing first. Brown the sausage in a pan, making sure to break it up into crumbles. Add the butter, along with the onion and celery. Cook for 5 minutes over medium-low heat, until softened. Add the chicken stock and thyme. Off the heat, add the chicken stock and thyme. Allow to cool slightly. Place the pieces of cornbread in a bowl. Add the chicken stock mixture to the cornbread. Add parsley, salt and pepper, and mix together until moistened.
• Adjust oven rack to middle position and heat oven to 400 degrees F. Place the sliced onion on top of a foil-lined rimmed baking sheet. Remove any giblets from the hens, and rinse them inside and out. Pat the outsides dry with a paper towel. Sprinkle the inside of the cavities with salt. Pack the cavities of the hens with the cornbread stuffing. All of it should fit.
• Tuck the wing tips under the body of the hens. Tie the legs together with kitchen string. Generously sprinkle the outsides of the hens with salt and pepper and use your hands to rub and evenly distribute the seasoning around the entire surface. Place the hens breast side down on top of the onions. Roast until backs are golden brown, about 25 minutes.
• Flip the hens breast side up and continue to roast for 15 minutes. Remove hens from oven and crank the heat up to 450 degrees F. Brush the tops with a little olive oil and pop back into the oven for 5-10 minutes, or until the skin is browned and the breasts register 160 degrees F and the thighs register 175 degrees F. Transfer hens to a serving platter or cutting board and allow to rest uncovered for 10 minutes before slicing into them.
  

TIP: If you do not stuff your birds, it will probably cook in less time, so go by temperature. The breast meat should be 160 degrees F.