Mix room temperature butter with orange zest, chopped rosemary and garlic, salt and pepper together and place in plastic wrap. Form into a 4-inch long log. Place in the freezer until firm and cut into tablespoon-sized disks.

Place the orange juice in the bottom of a dutch oven and preheat the oven to 275 degrees. Remove the gizzards from the chicken cavity and replace with orange slices, quartered onion and rosemary bundle. Rub the butter under the skin of the chicken breast and place the rest of the butter on the outside of the wings and legs. Sprinkle the rest of the chicken with salt. Place into the dutch oven with the lid and bake in the oven for 90-110 minutes until a thermometer inserted into the breast registers at least 160 degrees.