Cook and stir mushrooms and onion in margarine in 10-inch skillet over medium heat until all liquid is absorbed, about 10 minutes. Place mushroom mixture, cream cheese, salt and basil in blender container. Cover and blend on high speed, stopping blender occasionally to scrape sides, until smooth, about 2 minutes. Add parsley. Cover and blend on high speed just until parsley is chopped, about 30 seconds longer. Pour into serving dish. Cover and refrigerate until firm, about 3 hours. Garnish with mushroom slices and parsley sprigs if desired. Serve with crackers. 9 servings (2 ts per cracker); 85 calories per serving. Source: Betty Crockers Cookbook, 6th Edition