Rinse Cornish hens with water, then pat dry with paper towels. Salt and pepper the hens.
Preheat oven to 450°F/232℃. The high temperature at the beginning will crisp the hens—line the bottom of a baking pan, cast iron, or roasting pan with foil.
Use your index finger to carefully loosen the skin on top of the hens and rub them with garlic herb butter mixture. Plain butter works as well.
Lightly spray or coat the skin of hens with olive or cooking oil, then season with Italian and Creole seasoning.
Open up the cavity of the hens and stuff with half of the herbs, bay leaf, onion, garlic, and lemon. Just think of all those flavors infused in the meat!
Tuck the wings under the hen and use kitchen twine to tie the legs together. That helps the hens roast evenly and present well. No worries, if you don't have any on hand, it won't affect the taste.
Place hens in a roasting pan and place the extra herbs, garlic, lemon, and onions around them. Roast for about 20-25 minutes.
While the hen is roasting, whisk together chicken stock, white wine, and lemon juice. Set aside.
After the hens have roasted for 20-25 minutes, reduce the oven temperature to 350°F/177℃.
Carefully and heavily baste the hen with the chicken stock mixture. Continue roasting for about 25-30 minutes or until juices run clear and/or the thermometer reaches 165°F/74℃ (ensure the thermometer doesn't touch the bone!).
If using a flavor injector, inject hens with chicken mixture, baste and inject your hens every 10 minutes. This step is optional for those who choose to do it.
Remove the pan from the oven and let the chicken rest for about 5-10 minutes. Transfer fully cooked hens to a carving board, cut, and serve.