Beer Can Chicken, aka the perfect roast chicken

I think Tom said this came from his brother, Dennis. Meat so tender and moist, it falls off the bone.

2-3 onions, cut into thick slices (basically, you should have 4 slices from each onion)
4 carrots
6 lb chicken
2-3 Tbs butter
salt & pepper
2-3 sprigs of thyme
lemon
beer or white wine (some people use beer - hence the name - I prefer wine, but you can also use water or OJ)

Preheat oven to 425. Butter roasting pan, then line with onion slices. Lay carrots in pan, and put chicken in pan, resting on the carrots and onions. Remove giblets and save them for some other (gravy - eventually I'll post some) recipe. Rinse chicken inside and out, then pat dry. Place chicken in pan, on top of the onion and carrots. Use spoon to smoosh butter liberally under the skin. Season liberally inside & out with salt. Season outside with pepper. Cut lemon in half and squeeze juice in cavity. Peel the leafs of thyme off the stalks and crush them lightly, then sprinkle over the top of the chicken. Drape a piece of cheesecloth over the chicken, tucking it down and around the legs, etc. Pop the top on a can of beer/coke, empty/drink contents, and fill it back up halfway with white wine. Turn can so that it's horizontal, but with the tab-hole up - now shove the can into the cavity. Squeeze the other lemon half over the top of the chicken, then stick the lemon into the end of the chicken.

Roast chicken for 90 minutes, basting it quickly with pan juices every 20-30 minutes. Check for doneness by inserting a meat thermometer into the breast, then the thigh. The breast temperature should read 180 degrees, and the thigh should be 190 degrees.

When it's done, remove the can and lemon halves with tongs, then let the chicken rest for 10 minutes before carving.