Preheat oven to 220 degrees Celsius.
Line a pan with baking paper. Arrange on the pan pumpkin, sweet potato, carrot, and onion. Drizzle olive oil, sprinkle salt over the vegetables and bake 15-20 minutes until softened. If they start to brown, cover with aluminum foil. In the meantime, you can make the spinach cream.
Let it cool for a few minutes, remove the pumpkin skin with a spoon. Then, transfer the vegetables to a soup pot, including the liquid accumulated in the baking pan.
Add ginger, rosemary, coconut milk, salt, and black pepper. Add boiling water gradually, starting with 1 cup. Grind the vegetable with a stick blender. Add more boiling water until you get the desired consistency.
Taste and adjust seasoning if necessary.