Preheat the oven to 400˚F (200˚C). Place the cauliflower in a Dutch oven.

In the bowl of a small food processor, place the garlic, the Dijon mustard, the thyme, the rosemary, 3 tablespoons olive oil, 1 teaspoon of sea salt and 1/2 teaspoon pepper. Pulse until smooth and well-combined. Using your hands, rub the cauliflower with the mixture, making sure to do the bottom, and all the nooks and crannies. Place the cauliflower back in the Dutch oven and, using a small sharp knife, make 4-5 incisions in the top of the cauliflower to give room for the rub to get in. In a large bowl, mix the leeks, rutabaga, potatoes, carrots, 1 tablespoon olive oil and a sprinkle of sea salt and pepper. Arrange the vegetables around the cauliflower. Pour the vegetable broth, avoiding pouring on top of the cauliflower. Cover tightly with foil, cover, and place in the oven. Roast for about an hour, or until the cauliflower and the vegetables are tender. Uncover and broil for 2-5 minutes. Remove from the oven, take a picture and serve! Bon appétit!