1/2 lb. (8 sq.) unsweetened chocolate
1/2 lb. sweet butter, cut into cubes, plus butter for greasing pan
8 egg yolks
1 1/4 c. sugar
5 egg whites
1 tbsp. powdered cocoa
1 tsp. confectioners' sugar

Preheat oven to 350 degrees. Put chocolate squares and butter in saucepan. Set saucepan in skillet of boiling water. Keep the water at a simmer. Stir the chocolate and butter until chocolate is melted.

Combine egg yolks and sugar in bowl of electric mixer. Beat until mixture is light and lemon colored. Add chocolate sauce to egg mixture, stirring to blend thoroughly.

Beat egg whites until stiff but not "brittle". If the egg whites are too stiffly beaten, they will not fold in properly. Add half of the egg whites to the chocolate mixture and beat. Fold in remaining egg whites.

Butter the bottom and sides of an 8 inch springform pan. Pour in 3/4 of mixture into pan. Set the remaining chocolate mixture aside. This will be used as filling and frosting.

Place pan in oven and bake 1 hour and 15 minutes. When cake is done transfer it to rack. Let stand for 10 minutes. Remove rim from springform pan. Let cake stand until thoroughly cool. Spoon portion of reserved, uncooked chocolate mixture around sides of cake, smoothing it over like icing. Build it up slightly around top of cake. Spoon remaining on top of cake and smooth over. Hold a sieve over cake and spoon cocoa into it. Sprinkle over cake. Chill briefly. Add confectioners' sugar to sieve and spoon over top of cake.