Preheat the oven to 325 degrees.
Toss the mushrooms, shallots, and a few garlic cloves in the bottom of the skillet.
Drizzle them with some olive oil then season with sea salt and freshly cracked pepper, to taste.
Toss to coat evenly.
Rinse the chicken with cold water then dry very well with a paper towel.
Drizzle both sides of the chicken with olive oil then rub it in thoroughly.
Season the bird well with sea salt and freshly cracked pepper, to taste.
Place the chicken, breast side up, on the bed of mushrooms and stuff the cavity with a half a lemon, some onion wedges, a few cloves of garlic, some parsley, and a few fresh thyme sprigs.
Place into the oven and roast for 2-2 1/2 hours, basting with the pan juices every 30 minutes, until a meat thermometer inserted in the inner part of the thigh reads 170 degrees.
Remove from the oven and allow to rest for 10-15 minutes before slicing and serving.
Remove the mushrooms, shallots, and garlic from the skillet, serve on the side if desired.
Place the skillet on the stove over high heat. Reduce the liquid for a few minutes, stirring often. Add a dollop of butter, if desired; whisk well. Serve the sauce on the side. Enjoy.