Heat oil in a medium size saucepan. Add curry paste; cook 1 minute, stirring constantly. Add the ginger, garlic, coriander, cumin, brown sugar, and red pepper. Cook 1 minute or until fragrant.
Peel, seed, and cube butternut squash.
In a large saucepan, saute onions, celery, and carrots in butter until tender. Add the squash, cooked spices, water and broth. Bring to a boil; cook for 20-25 minutes, or until squash is tender.
Scoop out vegetables and puree in a blender or food processor in batches until smooth (using a bit of the liquid to ease the blending). Return to saucepan, add the coconut milk, and heat through. If soup is too thick, add a little more broth or water. Salt/Pepper to taste.
Serve as soup alone, with cut up cooked chicken, or over rice with cut up chicken.