In a small bowl, combine the salt, ground black pepper, Italian herb seasoning, smoked paprika, garlic powder, and crushed red pepper flakes. Mix thoroughly to create an even seasoning blend.

Pat the Cornish game hens dry with paper towels. Generously rub the prepared dry rub from Step 1 all over the hens, making sure to season both the inside cavity and the exterior skin for maximum flavor.

Preheat your oven to 425°F. In a roasting pan, arrange the fresh rosemary, thyme, quartered onion, garlic cloves, and half of the lemon slices to create a fragrant bed for the hens. Place the seasoned hens from Step 2 on top of the herb and vegetable mixture. Drizzle the olive oil evenly over the hens. I like to drizzle a little extra olive oil over the top to help the skin become extra crispy and golden in the oven.

Transfer the roasting pan with the hens and aromatics to the preheated oven. Roast for 50 to 60 minutes, or until an instant-read thermometer inserted into the thickest part of the breast registers 165°F. The skin should be deeply golden and crisp.

Remove the hens from the oven and let them rest for 20 minutes before serving. Slice the remaining lemon and use it, along with extra fresh thyme and rosemary, to garnish the hens. Serve warm, ideally over mashed potatoes for a comforting and elegant meal. Resting the birds makes them juicier, so I always let them sit before carving.