How to Make It
Preheat the oven to 400°. Rub the cauliflower all over with 4 tablespoons of the butter and season generously with salt and pepper. Put the cauliflower in a large cast-iron skillet. Add the garlic, thyme sprigs and the remaining 4 tablespoons of butter to the skillet. Roast the cauliflower for about 1 hour and 15 minutes, basting with the butter every 10 minutes, until browned and tender. Transfer the cauliflower to a serving plate. Discard the garlic and thyme sprigs.
Add the shallot to the skillet and cook over moderately low heat, stirring, until softened, about 2 minutes. Stir in the capers, soy sauce, lemon juice and half of the parsley and chives and season with salt and pepper. Spoon the pan sauce over the cauliflower and garnish with the remaining parsley and chives. Cut the cauliflower into wedges and serve.