1. Heat oil in large saucepan over medium-high heat and cook mushrooms, onion and garlic, stirring occasionally, 5 minutes or until tender. Stir in sauce, chicken broth and lemon juice. Bring to a boil over high heat. Reduce heat and simmer covered, stirring occasionally, 20 minutes. Add clams and mussels and simmer covered 5 minutes or until shells open. Remove shellfish as they open (discard any unopened clams or mussels). Add lobster and scallops and simmer 3 minutes or until done. To serve, arrange shellfish over hot spaghetti and top with sauce. Sprinkle, if desired, with chopped parsley.