The day before you plan to cook the chicken, season it well inside and out with salt and pepper. Stuff the cavity of the chicken with the garlic, 1 of the lemons, the bay leaf and thyme. Refrigerate.
(The bird can be trussed with butcher twine if you are so inclined, but it is not necessary.)
On the day/night you plan to cook the bird, take the chicken out of the refrigerator 30 minutes before you plan to roast it. Preheat the oven to 220°C.
In a pan large enough to accommodate the chicken, oil the pan lightly with olive oil, place the piece of sourdough in the center of the pan and then put the chicken on top of the bread.
Drizzle the bird with olive oil or brush with butter (we use olive oil at the Grill).
Place the pan in the oven and roast for 40 to 50 minutes, basting it every 12 to 15 minutes with the fat and drippings that render from the bird.
While the chicken roasts, assemble the glaze by combining all of the ingredients and whisking them together.
When the chicken is almost done (the juices are running pink and/or the legs are beginning to wiggle a bit when you give them a shake), take a pastry brush and slather on a bit of the crème fraîche glaze.
The glaze will begin to caramelize. Brush on another layer and let this last glazing caramelize.
At this point the chicken should be cooked through and nicely golden brown.
The sourdough underneath the chicken will be nicely browned and crisped on the side in contact with the pan, and moist and juicy on the side in contact with the chicken.
Let the chicken rest for 10 minutes before cutting it into serving pieces. Cut the sourdough into 2 to 4 pieces and serve with the chicken.
Garnish with lemon wedges and sprinkle it with Maldon sea salt.
(Alternatively, you can roast the chicken almost entirely through. Let it rest, split it in half and then glaze it with the creme fraiche under the broiler, brushing with the creme fraiche until you achieve golden brown, crackling skin.)