Combine all the spices/herbs in a small bowl, mix and set aside.
Cut the onion into quarters, and place the pieces in the bottom of the slow cooker. If using the Instant Pot, I recommend using the trivet and placing the onion pieces on top it.
Remove any giblets from the chicken, and rub the spice mixture over the entire bird.
Place the chicken on top of the pieces of onion and place the lid on. There is no need for any liquid to be added.
For Crockpot/Slow Cooking, cook on high for 4 hours or on low for 7, until the chicken is tender enough to nearly fall off the bone.
For Instant Pot Cooking, set for 25 minutes on Manual, and allow pressure to release naturally. ***When cooking in the Instant Pot, add 1 c. of water to the bottom of the pot. This is to help it come to pressure, and is not necessary for the Crockpot preparation.***