Melt chocolate and butter in a heavy saucepan over low heat. Beat eggs at medium speed with an electric mixer until frothy; gradually add sugar, beating until thick and pale (about 5 minutes). Add chocolate mixture, stirring until blended. Combine flour and baking powder; stir into chocolate mixture. Stir in nuts. Flour hands, and form dough into a 13" log. Place on a lightly greased baking sheet. Brush with egg white. Bake at 350F for 45 minutes; cool on a wire rack. Cut log with a serrated knife crosswise into 24 (1/2-inch) slices, and place on an ungreased cookie sheet. Bake at 350F for 10 minutes on each side. Remove to wire racks to cool. Per serving: 1969 Calories; 85g Fat (37% calories from fat); 35g Protein; 285g Carbohydrate; 394mg Cholesterol; 674mg Sodium From The Chocolate Archives, Dec 1997, http://www.choco.com