Wash squash, peel, remove seeds and cut into 2-inches pieces.
Place squash, potato and onion in a pot. Add water, paprika and butter. Cover the pot and bring to a boil over medium-high heat. Reduce heat to medium-low and simmer until vegetables are tender (about 20-25 minutes).
Blend the squash mixture in a blender until smooth. Return to the pot and heat through for 3-5 minutes. Add the heavy cream. Season with salt and pepper, stir well and serve. If soup is too thick, add more water.