Pre-heat oven to 450°F.
Check the cavity of the bird to see if there are packaged innards. If so, remove them.
Rinse the outside and inside of the chicken with cold water. Pat dry.
Sprinkle generously with salt and store uncovered in the refrigerator for 2-3 hours, or overnight.
Place the chicken on a large cutting board breast-side down with the tail facing you. Using sturdy kitchen shears, cut along one side of the backbone. Then, cut along the other side of the backbone to remove. Flip and press down on the breast bone until the chicken flattens. You should hear a cracking.
In at least a 12-inch cast-iron skillet or roasting pan, add the quartered onion, orange and petite potatoes. Place the chicken cut-side down on top.
In a small bowl, mix the spices with 3 tablespoons of softened butter. Rub the butter-spice mixture all over the chicken skin as well as some underneath the skin on the breasts.
Cook for 35 minutes. Pour in the apple cider and cook for another 10 minutes. Using an instant-read thermometer, check the temperature at the inner thigh. If it's 160-165°F, it's ready to pull. If not, continue cooking until it reaches that temperature range.
If cooking in a cast-iron skillet, transfer the chicken and potatoes to a cutting board and cover with foil. If using a roasting pan, pour the drippings into a skillet and cover. Discard the onion and orange quarters.
Over medium heat, whisk in cornstarch into the drippings. Keep whisking to prevent any lumps. Cook until the drippings thicken into a gravy.
Cut the chicken into pieces and top with fresh sage. Serve with apple cider gravy.