Heat a large Dutch oven over medium-high heat; coat with the olive oil. Season the hens with the poultry seasoning, seasoning salt and 1/2 teaspoon each Himalayan salt and pepper. Place, breast-side down, in the Dutch oven and cook until golden brown, 3 minutes. Turn and cook until golden brown on the reverse side, another 2 minutes.
Turn the heat down to the lowest setting and add the chicken stock and onions. Cover and cook the Cornish hens slowly until their juices run clear, 45 minutes. Reserve 1 cup of the cooking liquid for the Don't Block the Blessing Dressing.