In a small bowl, stir all the spice mix ingredients together.
To Make The Sauce: Heat the oil in a medium saucepan over medium heat. Sauté the squash and onion for about 5 minutes, or until the onion softens.
Add the vegetable stock and bring to a slow simmer. Cook for 15 to 20 minutes, or until the squash is tender when pierced with a fork. Season to taste with the spice mix, salt, pepper, and sugar, if necessary.
Transfer the vegetables and stock to a blender or food processor and puree until smooth. If using a blender, you may have to do this in batches. Return to the saucepan, cover, and keep warm. If the sauce cools before it's time to add it to the other vegetables, heat it very gently over low heat until just hot. Do not let it boil.
Preheat the oven to 400°F.
Cut the top off the pumpkin as though you were going to make a Halloween jack-o-lantern. Seed and scrape the inside of the pumpkin. Clean and reserve the seeds. Rub the lid and the inside of the pumpkin with ¼ cup of the spice mix. Wrap both the lid and the pumpkin completely in aluminum foil. Bake for 45 to 55 minutes, or until the pumpkin is fork-tender.
Spread the rutabaga cubes on a lightly oiled baking pan and roast for about 30 minutes, or until fork-tender. Spread the squash and turnip cubes on a baking sheet and roast for 5 to 20 minutes, or until fork-tender.
Spread the cipollini and pearl onions on a lightly oiled baking sheet and roast for 8 to 10 minutes, or until softened. Transfer the onions to a bowl and let cool. When cool to the touch, peel the onions.
Meanwhile, heat a large saucepan over medium heat. Add the olive oil and sauté the leeks, onions, cinnamon sticks, nutmeg, and jalapeno until the leeks begin to melt. Add the roasted rutabaga, squash, and turnip and cook until heated through. Add the hot squash sauce and the Yukon Gold and Peruvian potatoes and bring to a simmer. Remove from the heat, remove the cinnamon sticks, and sprinkle with the herbs. Stir them gently into the stew.
Remove the pumpkin from the oven and stand it upright. Ladle the stew into the cavity of the pumpkin.
Lay a slice of toast in the bottom of 8 warmed soup bowls. Sprinkle a little of the spice mix on the rim of the pumpkin. Use a carving knife to cut thin slices off the pumpkin rim. Arrange the slices around the bread, then ladle the stew over the bread.
Sprinkle the freshly cut rim of the pumpkin with more spice mix, and sprinkle the stew with more coarsely chopped herbs. Repeat the process until the stew and pumpkin are gone.
You may have a little leftover pumpkin, but not to worry! Puree it with some spice mix and brown sugar and use as you would canned pumpkin to make pumpkin pie.