Preheat the oven to 400 degrees F.
Prepare the cauliflower by carefully cutting off the bottom stalk and leaves without removing the core. You want the head to be firmly intact while roasting.
In a small mixing bowl, combine the olive oil, garlic, thyme, lemon zest and sea salt.
Flip the head of cauliflower upside down and pour half of the oil mixture into its nooks and crannies so that the sauce can evenly permeate the head. Turn it right-side up and place in a Dutch oven. Brush the remaining oil mixture on top of the cauliflower so that it is fully coated. Sprinkle with a little extra salt and black pepper to taste.
Cover the Dutch oven with its lid, and place on the center rack of the oven. Bake for 35 minutes, remove from the oven, take off the lid, and sprinkle the top of the cauliflower with the cheese.
Return the Dutch oven (with the lid off) to the oven. Roast for another 15 to 20 minutes, until the cauliflower is golden brown and at your desired level of crispiness and tenderness.
Remove, let cool for 5 minutes, then slice into florets, and enjoy!
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