Heat the oven to 400°F (200°C)
In a casserole with lid (or oven safe sauté pan) add the olive oil to medium-high heat. Once hot, add the onions and garlic and sauté for 2-3 mins.
Add the coconut milk, bay leaves, Dijon mustard, pomegranate molasses, lemon juice, green curry paste and water to the casserole. Once it simmers cook for 5-6 minutes until it starts to get thicker.
Slice the zucchini into round 1 inch slices. Set aside. Cut the stem off the whole cauliflower head so it lays flat. Instead of discarding, dice the leftover stem and set aside. We will add it into the casserole later.
Add the cauliflower into the casserole face down and use a soup ladle to pour over the sauce, make sure you get it everywhere. Flip over (right side up) and pour the sauce to cover. Now push the cauliflower to one side, and add your zucchini slices and diced cauliflower stem. Make sure these are also coated with the sauce.
Cover the casserole with a lid and cook covered in the over for 1 hr. Halfway in (at 30 mins) remove the zucchini and set aside in a separate bowl (to avoid overcooking). Use the soup ladle again to immerse with the sauce.
Once done, turn on the upper grill and roast for 2-3 mins until you get a nice crispy gold layer. Remove from the oven. Carve the cauliflower into thick pieces and serve with the zucchini slices.