In medium saucepan combine wine and, if desired, liqueur. Bring to boiling; reduce heat. Simmer, uncovered, about 10 minutes or until reduced to 1/2 cup. Add leek, rosemary, tarragon, salt, and pepper. Simmer, uncovered, 5 minutes more. Add whipping cream; return to boiling. Boil gently, uncovered, 2 to 3 minutes more or until slightly thickened. Makes about 3/4 cup sauce.