Preheat and Prep: Preheat your oven to 200°C (180°C fan). On a large baking tray, toss the cauliflower florets and chopped onion with 2 tablespoons of the olive oil, the salt, and the pepper. Make sure everything is well-coated. Add the unpeeled garlic cloves to the tray.

Roast the Vegetables: Spread the vegetables in a single layer to ensure they roast rather than steam. Roast for 30-35 minutes, turning halfway through, until the cauliflower is tender and has lovely caramelised, golden-brown edges.

Sauté and Simmer: While the vegetables are roasting, heat the remaining tablespoon of olive oil in a large stockpot or Dutch oven over a medium heat. Add the diced potato and cook for 2-3 minutes, stirring occasionally.

Combine Ingredients: Once the vegetables are roasted, remove the tray from the oven. Squeeze the soft, roasted garlic from their skins directly into the pot with the potatoes. Add the roasted cauliflower and onion to the pot as well. Pour in the hot vegetable stock.

Simmer the Soup: Bring the mixture to a boil, then reduce the heat and let it simmer gently for about 15 minutes, or until the potato is completely soft. What works best for me is to test a piece of potato with a fork; it should fall apart easily.

Blend Until Smooth: Remove the pot from the heat. Using an immersion blender, carefully blend the soup until it's completely smooth and velvety. If you don't have an immersion blender, you can transfer the soup in batches to a regular blender (be sure to let it cool slightly first and don't overfill it).

Finishing Touches: Stir in the double cream and the freshly grated nutmeg. Place the pot back on a low heat and gently warm through for a minute or two, but do not let it boil. Taste and adjust the seasoning with more salt and pepper if needed.

Serve: Ladle the hot soup into bowls. Garnish with a few reserved crispy cauliflower bits, a sprinkle of fresh chives, and a final drizzle of good-quality olive oil.