From Kenji:

    What I like about this recipe:

    • Achieve incredibly moist breast and tender dark meat every time thanks to even spatchcock cooking and precise temperature monitoring.
    • Get extraordinarily crispy, deeply flavorful skin by using a mayonnaise marinade that adheres herbs and promotes perfect browning.
    • Cook your chicken significantly faster than traditional methods because spatchcocking exposes more surface area to the oven’s heat.
    • Create a delicious, flavorful jus using the chicken backbone removed during spatchcocking, adding depth to your meal.
    https://frienji.kenjilopezalt.com/posts/for-best-roast-129086455?synced=1

    Ingredients

    For the Chicken

    Jus

    Instructions

    For the Chicken

    1. Adjust your oven rack to the center position and preheat oven to 425°F. Combine the mayonnaise, herbs, garlic, scallion, MSG (optional), salt, pepper, and lemon zest in a container just large enough to fit the head of an immersion blender. Blend until no large pieces of herbs remain. (Alternatively, use a food processor.)
    2. Using a set of sharp poultry shears, cut down either side of the backbone, removing it. Snip the backbone into a few chunky pieces and set them aside.
    3. Flip the chicken over skin-side-up, splay out the legs, and press down firmly along its sternum until you feel a small crack and the chicken lies flat. Tuck the wing tips behind the breast.
    4. Rub the mayo mixture all over all surfaces of the chicken, over and under, then transfer the chicken to a wire rack set in a rimmed baking sheet with the skin-side-up.
    5. Place in the oven and roast until the exterior is deeply browned an the internal temperature of the chicken registers 145 to 150°F, about 45 minutes. (I use the Combustion, Inc. Predictive Thermometer for this.
    6. Remove the chicken from the oven and allow to rest for ten minutes before carving and serving.

    Meanwhile, for the jus:

    1. While the chicken cooks, heat the olive oil in a medium saucepan over medium-high heat. Add the onions, celery, carrot, and chicken back pieces and cook, stirring, until very lightly browned, a few minutes. Add the herb stems, bay leaf, and chicken stock and bring to a simmer. Cook until the chicken is done roasting.
    2. Strain the broth through a fine mesh strainer, discarding the solids, then return the liquid to the saucepan. Add the lemon juice, soy sauce, and butter. Bring to a hard boil and cook until reduced to an intense jus. Season to taste with salt and pepper. Add parsley and stir in just before serving. Pour the jus over the carved chicken pieces, serving extra jus on the side.