Remove the chicken from the refrigerator 30 minutes before you begin cooking to allow it to reach room temperature. Preheat your oven to 220C/450F (standard) or 200C/430F (fan/convection), positioning a rack in the center.
In a bowl, combine the melted butter with the minced garlic, chopped herbs, salt, and black pepper. Squeeze the juice from two lemon wedges into the mixture, stirring to combine.
Place the chicken breast-side up in a roasting pan. Gently separate the skin from the meat over the breast and drumsticks using a dessert spoon. Carefully spoon the butter mixture under the skin, making sure to spread it evenly. Save a small portion of the butter mixture to coat the outside of the chicken.
Rub the remaining butter mixture all over the chicken’s exterior, ensuring the entire surface is well-coated. Squeeze the juice from the remaining lemon wedges over the chicken.
Stuff the cavity of the chicken with the used lemon wedges and rosemary sprigs. Secure the drumsticks together with kitchen string, and tuck the wing tips beneath the bird to prevent burning. Season the chicken generously with salt and pepper.
Scatter the onion quarters and halved garlic bulb in the roasting pan, then place the chicken on top. Pour the white wine or chicken broth around the chicken and drizzle the skin with olive oil.
Transfer the roasting pan to the oven and cook for 10 minutes at the preheated temperature. Then, reduce the heat to 180C/350F (all oven types) and continue roasting for 1 hour and 15 minutes, or until the internal temperature of the chicken reaches 75C/165F. Alternatively, check if the juices run clear when the thickest part of the drumstick is pierced. Baste the chicken twice during cooking—once at 30 minutes and again at 1 hour—using the pan juices.
Once the chicken is done, let it rest for 15 minutes before carving. Do not cover it during this time, as this will keep the skin crisp. Serve the chicken with the pan juices, discarding the onion but keeping the roasted garlic for added flavor.