Place thawed hens breast side up in a roasting pan.
In a small saucepan, melt butter over medium heat. Whisk in cornstarch to form a paste. Pour in orange juice and cranberry juice. Stir in brown sugar and rosemary. Increase the heat to high and bring to a simmer. Simmer until thickened.
Brush cran-orange glaze over hens, using all of the liquid. Sprinkle salt and pepper over hens.
Bake in the pre-heated oven for 60-65 minutes, until internal temperature reaches 165 degrees. Baste the hens every 20 minutes for best results.