Combine first three ingredients in a large bowl; toss well. Place pumpkin mixture on a baking sheet coated with cooking spray. Bake at 400° for 30 minutes or until tender.
Heat a large Dutch oven over medium-high heat. Coat pan with cooking spray. Add onion; sauté 8 minutes or until tender. Add garlic; sauté 1 minute. Add pumpkin mixture, 4 cups water, and remaining ingredients; bring to a boil. Reduce heat, and simmer 20 minutes.
Place half of pumpkin mixture in a blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Blend until smooth. Pour into a large bowl. Repeat procedure with the remaining pumpkin mixture.
Made the day before Thanksgiving with sugar pumpkin and butternut squash. Used a video tip from Food52 and rather than peel & cube the veg, cut in half and roasted skin on/seeds in/cut side down til done. Also roasted an apple for about the last 20min. Scooped out the cooled-down flesh and followed recipe, subbed veg broth for some of the water because we had it on hand. Adjusted seasoning to taste, adding a bit more spices and about 1tbs brown sugar. Thanksgiving morning, tasted again and used some apple cider to thin it a little.