In food processor, combine all ingredients except walnuts. Pulse until mixture is smooth. Remove to medium bowl; cover and chill until slightly firm. Shape into 5-inch ball or roll into 7 X 2-inch log.
Roll in toasted walnuts to coat evenly. Wrap in plastic wrap; chill until firm. Allow to warm at room temperature for 30 minutes before serving. May be kept in refrigerator for up to 5 days.