JAN'S VERY CHOCOLATE GATEAU AU CHOCOLAT
one 8½ to 9-inch cake
In the top of a double boiler, melt chocolate in vanilla over very hot water. In a deep large bowl, beat egg yolks lightly; gradually add ¼ cup confectioners' sugar, beating until thick and lemon colored. Add melted chocolate, ground almonds, butter, and cornstarch, mixing well. In a deep large bowl, beat egg whites with a pinch of salt until foamy; gradually add ½ cup confectioners' sugar, beating until stiff, but not dry, peaks are formed. Fold one-third of beaten egg whites into chocolate mixture, then fold in remaining beaten egg whites. Turn mixture into lightly buttered 8½ to 9-inch diameter spring-form pan. Bake in a preheated moderate oven (375 degrees F.) for 35 to 40 minutes or until a cake tester inserted in center of cake comes out clean. Cool thoroughly on a wire rack, then unmold and transfer to a cake serving plate. Frost top and sides of cake with icing. Garnish cake with sliced almonds or as desired.
To prepare icing, bring Creme Fraiche to a boil in a small heavy saucepan over moderate heat. Reduce temperature to low and add chocolate, bit by bit, blending well. Remove from heat and cool (icing should be consistency of thick spreadable chocolate).
Note: Use a high quality chocolate such as Lindt or Tobler or Ghirardelli brands. For a sweeter chocolate flavor, use all semisweet chocolate.
Note: May omit almonds; use ¾ cup plus 1 teaspoon sifted cake flour and may add ½ teaspoon almond extract.
In a medium bowl, combine cream and buttermilk, blending well. Cover loosely with plastic wrap and allow to stand at room temperature for 12 hours or until fairly thick. Cover tightly and refrigerate at least 4 hours to continue to thicken. May keep in a tightly sealed container in the refrigerator for up to one week. A tangy flavor will continue to develop.