In a small bowl, combine the paprika, smoked paprika, salt, onion powder, dried thyme, garlic powder, cayenne and black pepper. Set aside.

Place the onion pieces in the bottom of your slow cooker.

Remove any giblets from the chicken and stuff it with rosemary, garlic and lemon wedges (or whatever herbs and aromatics you like).

Rub the outside of the chicken with the spice mixture. If you like you can also rub some of the spices on the inside of the cavity and beneath the skin covering the breasts.

Place the spice rubbed chicken, breast side down, on top of the onion pieces and cover the slow cooker. You won't need to add any extra liquid.

Cook on high for 4 hours or on low for 7 hours, or until the chicken is tender and falling off the bone. Remove from the slow cooker and serve.