When making roast chicken, the key to getting crispy, golden skin is to season your bird in advance and leave it in the fridge overnight. The chicken roasts directly on top of a baguette, which absorbs the pan drippings for a side as tasty as the main event.
The day before roasting, combine butter in a bowl with zest of one lemon (reserving the lemon), garlic, chives, and thyme. Season with salt and pepper and mix to combine. Dry the chicken with paper towels and place on a roasting pan fitted with a rack. Season chicken with salt and pepper, inside and out. Using your fingers, gently release the skin from the breast on either side of the breast bone. Place a heaping tablespoon of the compound butter under the skin on each side and smooth down to coat each breast. Do the same at the other end, where the thigh joins the open cavity. Distribute the remaining butter on each side under the leg skin. Place chicken in the refrigerator, uncovered, to allow the skin to dry.
The next day, preheat the oven to 500 degrees F. Roughly chop the celery, onion, and carrot and place inside the chicken cavity, along with leftover herb stems and half the zested lemon. Cut the baguette to approximately the length of the chicken and place, open-faced, on a rimmed baking sheet. Lay the chicken on top of it. Pour water or chicken stock in the pan so the bread doesn’t burn. Bake, 10–12 minutes.
After 10 minutes, chicken will begin to brown. Add more water or stock to the pan if the bread looks too dark. Reduce oven temp to 400 F and continue cooking, 35–55 minutes, depending on chicken size. (Final internal temperature should be 165 degrees F at the thickest part of the thigh.)
Test the chicken for doneness by sticking a knife into the thickest part of the thigh—the juices should run clear (i.e., not pink). When done, remove from oven and let the chicken rest 5 minutes before carving. To carve, first remove the wings. Next, cut the skin close to the leg, then cut from the back and follow the bone along the joint and remove the leg. Remove the breasts by cutting down the middle, following the bone (save the rest of the chicken carcass for stock). Cut the baguette into four pieces and serve with the cut chicken on top.