In 2-quart saucepan on Wolf cooktop over medium heat, bring wine, shallot, thyme, bay leaf and peppercorns to a boil. Continue to boil about 35 minutes to reduce mixture to about 1/4 cup. Add beef stock and bring to a boil, cooking until mixture is reduced by half or 1 1/4 cups. Adjust salt and pass through a fine strainer. Return to saucepan and bring to a gentle simmer. Just before serving, whisk in butter.