In a large pot, melt butter. Add onions and saute until tender.
Add squash, water, bouillon, marjoram, black pepper, and cayenne pepper. Bring to a boil, cover, cook on medium-high heat for 15 minutes or until squash is tender. Remove from heat and add cream cheese.
Puree cooked vegetables and cream cheese with a hand blender* until smooth. Serve garnished with Parmesan and croutons.