Flour and butter an 8-inch round cake pan. Cut a round of waxed paper to fit the bottom, butter it, and place in the pan. Preheat the oven to 425F. In a small saucepan over very low heat or in a microwave oven, melt the chocolate with the butter. Set aside. In the top of a double boiler over very hot water, whisk the eggs with the sugar. Beat over hot water until the sugar dissolves and the mixture is just lukewarm. Remove the top of the double boiler from the heat and beat the eggs until they quadruple in volume and become quite thick. Fold the flour into the eggs. Stir 1/4 of the egg mixture into the chocolate. Then, fold the chocolate back into the rest of the egg mixture. Pour the batter into the prepared cake pan. Bake for 15 minutes; the cake will be liquid in the center. Cover and freeze the cake in the pan overnight. To unmold the cake, carefully dip the bottom of the pan in hot water and invert onto a cake plate. Remove the pan and gently peel off the waxed paper. Decorate the cake with the whipped cream and shaved chocolate. Refrigerate until serving. Puree the raspberries and their juice in a blender or food processor. Pass the puree through a fine sieve and serve a tablespoon of the sauce with each portion.