Place 1/4 cup chicken broth in a large saucepan; bring to a boil. Add onion and crushed red pepper; cook 5 minutes or until tender. Add remaining 2 3/4 cups broth, squash, salt, and water; bring to a boil. Cover, reduce heat, and simmer for 20 minutes. Add rice; cover and simmer 20 minutes or until squash and rice are tender.
Place peanut butter and half of soup in a blender; cover and process until smooth. Pour purée into a bowl. Repeat with remaining soup, and add to bowl, stirring well. Ladle soup into individual bowls; garnish with parsley, if desired.