Prepare the veggies. Chop the onion and garlic, cut the leeks into thin rounds. Peel the pumpkin, remove the seeds and cut into 1 inch cubes.
Start sautéing the onion in a pot with the olive oil over medium heat. Add the garlic and pumpkin cubes after 5 minutes and continue cooking without adding any liquids for 2-3 minutes.
Add water, salt, ground black pepper and nutmeg. Cook for 30 minutes over low, until the pumpkin gets soft.
Add the cream and the leek and purée it in a blender, food processor or with an immersion blender. Cook for another 10 minutes to take out the raw flavor of the leek.
Serve warm. It is good as is, or sprinkle with spring onions and add fresh ciabatta or baguette.