Preheat the oven to 400°F. Position racks in the bottom of 2 medium-sized roasting pans and coat them both with nonstick spray.
Season the cavity of each hen with salt and pepper and rub a tablespoon of softened butter liberally over the skin. Season the outside with salt and pepper and tie the legs together with kitchen twine.
Arrange 3 hens, breast side up, in each roasting pan, being sure to leave a little space between them. Add a 1/2-inch of water to the bottom of each pan and place them in the oven.
Roast the hens for 30 minutes, then baste with the pan juices. Return them to the oven, rotating the position of the roasting pans (top to bottom and front to back) to ensure even cooking.
Continue roasting the hens for an additional 20 to 30 minutes or until an instant-read thermometer inserted in the thickest part of the thigh registers 165°F.
While the hens are roasting, heat the butter in a small saucepan over medium heat. Add the garlic and cook until soft and fragrant, 2 to 3 minutes. Season with a pinch of salt and pepper, then add the bourbon.
Bring the mixture to a slow simmer, stir in the honey and continue cooking, stirring frequently, until the mixture thickens to a syrupy consistency, 7 to 10 minutes. Reduce the heat to low and keep warm until the hens are finished roasting.
Remove the hens from the oven and brush them with the glaze. Increase the oven temperature to 450°F and return them to the oven just long enough for glaze to caramelize, about 5 minutes. Remove and brush with any remaining glaze if desired.
Allow the hens to rest for 10 minutes before serving.