Place chicken between two sheests of heavy- duty plastic wrap, and flatten to 1/2 " thick, using a meat mallet or rolling pin. sprinkle with salt and pepper. Cook chicken in butter in a large pan over medium high heat 5-7 minutes on each side or till done. Remove chicken to platter, reserve drippings in pan. Set aside chicken and keep warm. Add whiskey to drippings in pan; cook over high heat. deglazing pan by scraping particles that cling to bottom. Cook till whiskey is reduced by half. Add whipping cream, green onions, and chopped tarragon; bring to a boil. Cook, stirring constantly; till thickened. Spoon sauce over chicken. Garnish. if desired. Serve immediately.