Preheat oven at 375°.
Butter an ovenproof roasting pan. Cover the bottom of the roasting pan with the thinly sliced lemons and add the thinly sliced leeks over it.
Pat the chicken dry, salt and pepper all over, Place the chicken on top of the leeks. Salt and pepper generously. Add the garlic cloves, juice from 1 lemon and the white wine around the chicken.
Place in the warm oven and lower the heat to 350°.
Check while cooking to make sure that the lemons and leeks do not burn and baste the chicken with juices every 15-20 minutes. Add more wine if needed.
Once the chicken is nice and golden, 45 to 50 minutes and no more juices are running when pierced, remove from the oven and let sit covered for 5 minutes before serving.
Cut into 4 pieces and serve with the leeks and lemons relish.