This is a French–influenced variation of a popular seasonal pumpkin soup, and it makes a fine first course for any dinner spread or as part of a Moroccan meal. While fresh pumpkin is more traditional in this recipe, butternut squash is easy to prepare and a good alternative.
Combine first 7 ingredients in a large saucepan; bring to a boil. Cover, reduce heat, and simmer 10 minutes or until vegetables are tender.
Place half of squash 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 pureed mixture into a large bowl. Repeat procedure with remaining squash mixture. Return pureed mixture to pan over low heat. Add milk and butter to pan; cook 3 minutes or until thoroughly heated. Serve with yogurt and cilantro.