Preheat your oven to 400 degrees F.

Pat your cornish hens dry with a paper towel and place them in a large-rimmed baking dish. 

In a small bowl, combine the olive oil, salt, garlic powder, dried thyme, onion powder, paprika, and black pepper. 

Drizzle the oil mixture over the cornish hens and rub it all over, making sure to coat the hens on all sides.

Fill the cavity of each hen with two-quarters of the onion, half of the carrot, half of the celery, one clove of garlic, and one sprig of rosemary. 

Tie the legs with kitchen twine and tuck the wings under the bird. This will prevent them from burning in the oven. 

Roast the hens for 50-55 minutes or until an instant-read thermometer registers 160 degrees F. Baste the hens with juices from the pan after 25 minutes. 

Remove the hens from the oven and cover the pan with aluminum foil.

Rest the hens for 10 minutes, or until the internal temperature registers 165 degrees F. 

Serve the cornish hens whole or carved with a garnish of fresh herbs or flakey sea salt. Enjoy warm. 

Store any leftover hen in an airtight container in the fridge for up to three days.