Pre-heat the oven to 425' F.
Wash and pat the chicken dry, remove and excess fat. Season the chicken cavity with salt and pepper.
Squeeze the juice from 1 orange, then set the juice aside. Put the squeezed orange halves and garlic inside the chicken. Skewer the cavity closed and truss the bird.
Brush the chicken all over with the melted butter and then season with salt and pepperand sprinkle with herbes de provence. Cut the remaining 2 oranges into quaters.
Coat the bottom of a roasting pan with the oil, then place the chicken in the pan, with the orange quaters.
Roast chicken for 20 min then reduce oven temperature to 350' F. Continue to roast the chicken, basting with the pan juice for another hour or until an instant-read thermometer inserted into thickest part of thigh reads 165'F.
Transfer chicken and oranges to serving platter, placing chicken breast-side down. Let rest loosely covered with aluminium foil for 10 to 15 minute.
Tip the roasting pan and spoon out any excess fat. Place the pan over medium heat, add chicken stock and deglaze the pan by scraping up the browned bits with wooden spoon. Add the orange juice and bring to boil, then boil until the liquid is reduced to about 2/3 cup then season with salt and pepper.
Remove the trussing string from chicken, turn chicken breast side up and carve. Add any juices from the chicken to the sauce. Serve the chicken with the sauce and orange wedges.
(for thicker sauce add flour).