How to Make It
In a medium bowl, blend the butter with the clementine zest, grated garlic and chopped thyme. Run your fingers under the turkey breast and thigh skin to loosen it, then spread the butter mixture under and over the skin of the breast and thighs. Season the turkey inside and out with salt and pepper. Transfer to a rack set in a roasting pan and let come to room temperature, about 1 hour.
Preheat the oven to 400°. Roast the turkey for about 30 minutes, until lightly browned. Add the chicken stock to the roasting pan and roast for 30 minutes. Scatter the clementine halves, garlic heads and thyme sprigs in the pan. Roast for about 1 hour longer, rotating the pan a few times, until an instant-read thermometer inserted in the inner thigh registers 165°. Transfer the turkey to a cutting board; let rest for 30 minutes. Transfer the clementines, garlic heads and thyme to a plate, tent with foil and keep warm.
Meanwhile, skim the fat off the pan juices and transfer the juices to a medium saucepan. Squeeze the roasted garlic from 1 head and whisk into the pan juices. Bring to a boil over moderately high heat and cook, whisking frequently, until slightly reduced, about 5 minutes. Season the roasted garlic jus with salt and pepper. Carve the turkey and transfer to a platter. Arrange the roasted clementines, garlic heads and thyme around the carved turkey and serve with the jus.