Brown leeks and shallot in the olive oil, using a large pot. Add pumpkin and potato chunks and brown them for a few seconds. Add the broth, cover, and cook for about 20 minutes on medium heat (until tender).
Blend hazelnuts, curry, cinnamon, and brown sugar and set apart.
Salt to taste, add heavy cream, and stir.
Serve the soup hot, sprinkled with the chopped curried hazelnuts.
I made my broth with minimum effort: I boiled a carrot, a shallot, a few sprigs of parsley and a few of thyme, 3 allspice corns and 3 of juniper.