Cut pumpkin in half, drizzle with olive oil and toss with salt, then place on a baking sheet face down. Roast until pumpkin is tender when pierced with the tip of a sharp knife, about 40 minutes. Let cool enough to remove skins.
Meanwhile, while pumpkin is baking: Heat olive oil in a large saucepan over medium heat and sauté onion, celery and leek until tender, 6-8 minutes. Add garlic and continue to sauté until fragrant, about one more minute. Add veggie stock, carrot and spices and bring to a simmer. Once pumpkin skins have been removed, add to saucepan.
Garnish with toasted pumpkin seeds, fresh thyme or sage, a dollop of fresh sour cream. (vegan of course)
Toss seeds in a bowl with the olive oil, salt and pepper. Spread the seeds in a single layer on a baking sheet and bake for about 30 minutes or until golden brown; stir occasionally. Serve with soup immediately.