Make 4-5 aluminum balls and place in the bottom of the slow cooker to create a rack for the chicken in the slow cooker. You can also wrap 4-5 medium potatoes in the tinfoil and place those in the bottom of the slow cooker for an easy side dish.
Pat the chicken dry with a paper towel. Truss the chicken legs together for a better presentation and to hold the chicken together better. Mix together all of the spices with the lemon juice. Rub the spice rub all over the chicken.
Stuff the lemon into the chicken cavity and place the chicken on top of the aluminum foil balls or wrapped potatoes. Cover and cook for 4-5 hours on high (or 7-8 hours on low) until the juices run clear and chicken is cooked to 165 degrees. Exact cooking time will depend on the size of the chicken.
Optional for crispy skin: Preheat the broiler and cover a baking sheet with foil. Place the chicken on the baking sheet and brush with olive oil. Broil until the skin is nice and crispy, be careful the skin doesn't burn.