Place a rack in the middle of the oven; preheat to 300°. Pat chicken dry with paper towels. Place the bird on a rimmed baking sheet. Season the entire chicken all over with salt. Season the cavity, as well.

Whisk 5 Tbsp. gochujang and ¼ cup extra-virgin olive oil in a medium bowl until combined. Finely grate 2 garlic cloves (from one of the whole head of garlic) into gochujang oil. Using a spoon, peel 1-inch piece of fresh ginger), then grate into gochujang oil; whisk to combine.

Cut what’s left of the head of garlic in half crosswise, and stuff it into the cavity of the chicken. Tie legs together with kitchen twine. Using a pastry brush, brush the gochujang oil over the chicken, you will have some left over for the cabbage.

Remove one layer of the outer leaf of cabbage if need (sometimes they are a little dried out and floppy) then cut crosswise, remove the core, and cut each half into four pieces. Toss in remaining gochujang oil until well coated. Season lightly with salt and pepper and toss again to combine.

Arrange cabbage in a 12" cast-iron skillet, scooting them toward edges of pan to make space for chicken. Place chicken in the middle of cabbage.

Roast chicken and cabbage for about 2–3 hours (cooking time will vary depending on oven temperature and size of the bird, so make sure you check in after 90 minutes to assess.)

About halfway through the cooking time, remove the skillet from the oven to toss cabbage over in juices and prevent burning.

Cooking is done when the skin is a deep reddish-golden brown color, and a meat thermometer reads 165 degrees.

Remove from oven and let rest for 10-15 minutes before cutting chicken. Don't skip this step: Letting the bird rest helps the juices in the meat to settle and make the meat more juicy. Carve chicken and arrange it on a plate with caramelized roasted cabbage to serve.