Butter the bottom and sides of a 1-cup round baking dish with 1/2 teaspoon butter. Sprinkle buttered surface with 1 tablespoon Parmesan cheese; set aside. In a small saucepan, melt remaining butter; stir in flour until smooth. Gradually stir in milk. Add chives and Worcestershire sauce. Bring to a boil; cook and stir for 1 minute or until thickened. Remove from the heat. Stir a small amount into egg yolk; return all to pan, stirring constantly. Transfer to a bowl; set aside. In a bowl, beat egg white until stiff peaks form; fold half into yolk mixture. Fold in Swiss cheese, then remaining egg white. Pour into prepared baking dish. Sprinkle with remaining Parmesan cheese. Bake at 375° for 30-35 minutes or until lightly browned and a knife inserted in the center comes out clean.