Method
1-Preheat the oven to 425°F (220°C), or: Preheat the oven to 425°F (220°C), or 400°F (200°C fan). Place the prepared sweet potatoes, carrots, whole peppers, onions and garlic in a large roasting dish. Use a second dish if the vegetables are piled up. Drizzle with all the olive oil, including the exposed garlic cloves, and season with salt and pepper.
2-Cover the dish with foil and roast: Cover the dish with foil and roast for 30 minutes. Carefully remove the foil and roast for another 15-20 minutes, until the thickest sweet potato and carrot pieces are completely tender and the edges have some color. Larger pieces may need longer. Remove any vegetables that are ready earlier; loosely shield the garlic if it browns before softening.
3-Let the vegetables cool for about 5: Let the vegetables cool for about 5 minutes, or until safe to handle. Squeeze the soft garlic cloves out of their skins. Open the peppers and discard the stems, cores and seeds; peel off any heavily blackened skin.
4-Transfer the vegetables, squeezed garlic and any: Transfer the vegetables, squeezed garlic and any unburned roasting juices to a large saucepan. Add the vegetable stock and blend with an immersion blender until smooth, keeping the head submerged to avoid splashes.
5-Stir in the oat cooking cream: Stir in the oat cooking cream. Add more stock, a little at a time, until the soup reaches your preferred thickness. Warm over medium-low heat for about 5 minutes, stirring, until hot throughout. Taste and adjust the salt and pepper.
6-Ladle into bowls and finish with parsley,: Ladle into bowls and finish with parsley, chili flakes and a little extra cream if you like.