Season the back of the bird well with sea salt and freshly cracked pepper, to taste. Place the bird, breast side up, on a roasting rack in a roasting pan.

Mix the butter, zest from 1 orange, 1 minced garlic clove, and chopped thyme until well combined.

Gently separate the skin from the breast of the chicken, and rub some of the butter mixture under the skin on each side. Rub a bit more butter on top of the chicken skin, wings, and legs. Season with sea salt and freshly cracked pepper, to taste.

Fill the cavity with 2 orange wedges, 1 onion wedge, one garlic clove, and the thyme sprigs. Tie legs together with kitchen twine. Scatter the remaining oranges and onions around the chicken. Dot oranges and onions with a touch of the remaining butter mixture.

Roast for 30 minutes. Brush the chicken with the remaining butter mixture. Flip oranges and onions. Rotate the sheet, and roast for 15-20 minutes more. Remove oranges and onions if caramelized. Roast chicken until juices run clear and an instant-read thermometer inserted into the thickest part of a thigh reaches 165 degrees, 10 to 15 minutes more.

Let the chicken rest for 10 minutes before slicing and serving with the roasted onions and oranges on the side. Enjoy.