(Optional): you can wash your chicken before you start, but it is not necessary. If you do choose to rinse it off, just make sure to pat it dry with a paper towel. In order for the skin to get very crispy, the skin needs to be totally dry from water.
In a 9X13 baking dish, place chicken in dish, tuck the wings in towards the bird for a nice presentation, and stuff the cavity with the onions, lemon, and rosemary.
(Optional): If you are presenting this chicken to special guests, you may want to tie the legs together with kitchen string. It is not necessary, but does give a nice presentation once cooked.
Drizzle the avocado oil all over the chicken, and use your hand to really rub it on. You want oil all over the skin. Then, sprinkle the chicken liberally with salt and pepper.
Bake for 1 hour and 40-50 minutes, or until the internal temperature of the chicken is 165 degrees Fahrenheit. Small birds will cook faster, so check the temperature often.
**If you do not have a thermometer, just take a knife and cut open the skin between the leg and thigh. If the juices are clear, then the chicken is done. If not, then put it back in the oven for 10 more minutes, then check again.
Cover the chicken with foil and let it rest for 10-15 minutes before cutting into the meat.