Season thighs with salt and pepper. Place skin-side down in a dry oven-safe skillet over medium heat. Cook until skin is deeply golden and crisp, flip briefly, then remove.
Add cabbage wedges to the rendered chicken fat. Sear cut sides until browned, seasoning with salt and pepper. Add thyme.
Add stock to come about ¼ of the way up the cabbage. Nestle chicken back in, skin-side up. Transfer to a 400°F oven and cook until chicken reaches 165°F and is golden, about 30–35 minutes.
Toss julienned apple with chives, lemon zest and juice, olive oil, salt, and pepper. Chill until ready to serve.
Remove chicken and cabbage. Sauté shallot in the pan, add Dijon, deglaze with a splash of water, and scrape up browned bits. Season with lemon juice, salt, and a pinch of MSG. Swirl in butter.
Plate cabbage and chicken, spoon sauce over top, and finish with apple slaw.
