Preheat the oven to 425° and position the rack in the lower third of the oven.
In a small bowl, add the softened butter, minced garlic, minced herbs and lemon zest. Add salt and pepper, to taste.
Add 1 cup of water to the roasting plan. Scatter the onion, lemon slices and herb sprigs in the pan. (*Note 2)
Pat the chicken dry and truss. Rub half of the butter mixture under the skin and the other half over the top of the chicken. Season with salt and pepper, to taste.
Set the whole chicken breast-side-up on a rack in the roasting pan.
Roast for about 60-75 minutes, until an instant-read thermometer inserted in the inner thigh registers 175° to 180°.
Remove the chicken from the oven, cover with foil and let rest for 10 minutes.
Using tongs, tilt the chicken to drain the cavity juices into the pan before transferring the chicken to a cutting board.
Slice immediately and enjoy.
Notes
If using dried herbs, use 1/8 tsp for each: Rosemary, thyme and sage. Also add 1/8 tsp to the water in the roasting pan, for a total of 1/4 tsp.
Watch the water level..if using a larger roasting pan start with 2 cups of water. Add more during cooking as needed.