Chop the leek, and peel and chop the butternut squash and pumpkin into chunks. Heat the oil in a saucepan and gently cook the leek and butternut squash and pumpkin until it starts to soften and turn golden.
Pour water into the saucepan, until the butternut squash and pumpkin is covered. Add one vegetable stock cube in the pan and cinnamon. Bring to the boil and simmer until the squash and pumpkin is very soft.
Remove from heat and use a hand held food processor to blend until smooth. If you prefer a thinner consistency, add a little more water. Season to taste with salt and pepper, and stir through the cream.
Ladle the soup into bowls, drizzle over a bit of cream and sprinkle with pumpkin seeds if desired!