Preheat the oven to 350 °F. Combine butter and 1 tsp rub per bird. Rub each hen with seasoned butter being sure to place some butter under the skin at breast and thigh. Insert half a lemon into the cavity of each bird.
Place carrots, onion, celery, and garlic in an even layer in a 9-by-13-inch baking dish or roasting pan. Place the hens on top of veggies, breasts facing up. Roast until the juices run clear and the hens are golden brown, 45 minutes to 1 hour. If you like, you can baste the birds with juices from the pan or melted butter.
Remove from oven, and allow to cool a bit before serving. If you'd like to infuse your hens even further, try our Spiced Turkey Brine!