Cake
1 cup semi-sweet chocolate
1/2 cup butter
1/2 cup flour
4 eggs, separated
1/4 teaspoon cream of tartar
1/2 cup sugar
2/3 cup semi-sweet chocolate chunks
Chocolate Sauce
1/3 cup semi-sweeet chocolate
3 tablespoons sugar
1/4 cup evaporated milk
1/2 teaspoon butter
Cake
Heat oven to 325°F. Grease 9 inch springform pan. Melt chocolate and butter together, stirring till smooth. Cool 5 minutes. Stir in flour. Stir in yolks till well blended. Beat whites and cream of tartar together till foamy. Beat in sugar 1 tablespoon at a time till soft peaks form. Fold 1/4 of whites into chocolate mixture to lighten. Fold chocolate mixture into remaining egg whites. Spread in pan and sprinkle with chocolate chunks. Bake 35-40 minutes till toothpick inserted in center comes out clean. Top will appear dry and cracked. Cool 10 minutes. Remove side of pan and cool completely on rack. Serve with chocolate sauce and whipped cream.
Chocolate Sauce
Bring chocolate, milk and sugar to boil, stirring constantly. Remove from heat and stir in butter.