Preheat the oven to 220ºC.

Brush clean the mushrooms and slice any larger ones in half. Toss with olive oil and roast for 15 minutes in a large baking dish.

Meanwhile, cut two of the onions into quarters and separate the onion layers into petals. Finely chop the remaining onion and set aside.

Add the onion petals to the mushrooms and roast for another 15 minutes, or until the mushrooms and onions are golden.

While the mushrooms and onions are roasting, melt the butter in a large frying pan over medium heat. Add the finely chopped onion and cook for 5-6 minutes or until soft. Add the wine and simmer until nearly evaporated. Add the spinach and most of the chilli and stir for 6-7 minutes, or until the spinach has defrosted and most of the liquid has evaporated. Stir in the crème fraiche and season with salt to taste. Set aside.

Bring a large saucepan of lightly salted water to the boil over high heat. Remove the cauliflower leaves and tough base of the stem, but keeping the stalk intact. Slice the cauliflower from top to bottom into 5 mm-thick ‘steaks’, saving the florets that don’t stay intact. Carefully drop all the cauliflower bits (minus the tiny crumbs) into the boiling water and simmer for 2 minute, then drain into a colander and rinse with cold water.

Preheat the grill (broiler) to high. Reserve a few of the herbs for the garnish, then combine the rest with the lemon juice and stir through the mushrooms and onions. Spread the spinach mixture over the top, mixing together gently, and then sprinkle over any cauliflower crumbs. Place the blanched cauliflower over the top, then add the grated cheese. Grill for 5-10 minutes or until the top is golden and bubbly. Sprinkle with the remaining chilli and herbs, then serve immediately.