Preheat the oven to 180°C (350°F) and line a baking tray with baking paper. For the crisps, slice the sweet potato into very thin slices using a mandoline. Put the slices in a bowl with the coconut oil, season to taste and toss until coated.
Place the sweet potato evenly on the baking tray and pop them in the oven. After 10 minutes, flip them over to cook the other side. Bake for another 5 minutes until crisp then remove from the oven and set aside.
For the soup, break up your heads of broccoli and cauliflower and steam them for 5 minutes. Meanwhile, put the onion, leek and garlic in a saucepan over medium heat and sauté in the olive oil until translucent.
Transfer the mixture to a blender with half the stock. Blitz until smooth and pour back into the soup pan. Place the steamed cauliflower and broccoli in the blender with the remaining stock and blitz again until silky smooth. Pour this into the soup pan with the onion and leek mixture and stir.
Add the herbs, chilli flakes, cheese and coconut cream and season with salt and pepper. Serve with a drizzle of olive oil, a sprinkle of black pepper, some chopped parsley and the sweet potato chips.
Store the soup in a container in the refrigerator for up to 3 days or freeze for up to 3 months.