Place the chopped vegetables into your slow cooker, drizzle them lightly with olive oil and sprinkle with salt and pepper. Put the chicken on top, nestling it in with the vegetables.
Place the sprigs of rosemary inside the chicken. Then, rub the chicken with olive oil and sprinkle it with salt, pepper, and parsley. Sprinkle the diced garlic over the chicken and vegetables.
Cook the chicken on low for 4 to 6 hours, or until the chicken reaches an internal temperature of 160 degrees F. The cooking time will depend on the size of the chicken. Do not add any additional liquid; the juice from the chicken will mix with the olive oil and cook the vegetables to perfection.