Preheat oven to 350n degrees. Butter and flour a 9 inch cake pan. In a bowl, combine the chocolate and butter and melt over a double boiler. Set aside to cool. In a mixer, using a wire whisk, whip the egg yolks and 3 tablespoons of sugar until light and ribbony. Beat in the chocolate mixture.
In another bowl, beat the egg whites and salt until soft peaks form. Slowly add the remaining 2/3 cups of sugar and continue to beat until stiff peaks form. Fold in the flour to the chocolate mixture and then fold in 1/3 of the egg whites into at a time until it's thoroughly incorporated. Pour into prepared cake pan.
Bake for 35 miinutes or until done. To check for doneness, insert a paring knife or toothpick in the center of the cake. It should come out dry. Remove from the oven and cool on a rack.
To make the raspberry filling
Puree the raspberry preserves in a food processor and stir in the liquor.
After the cake has cooled, slice it horizontally into 3 equal layers. S
Spread half of the raspberry filling on the bottom layer. Top with a second layer of cake. Spread the remaining raspberry filling and top with the last layer of cake. Chill for an hour.
To make the frosting
In a bowl, combine the chocolate and butter. Melt over a double-boiler. Bring the cream to a boil. Sitr into the melted chocolate. Cool until it reaches glazing consistency. Spread over and around the cake. Chill for 30 minutes before serving. Serve with whipped cream or ice cream.
Eduard Sacher completed his culinary training in Vienna with the Royal and Imperial Pastry Chef at the Demel bakery and chocolatier, during which time he perfected his father's sachertorte recipe. The cake was first served at the Demel and later at the Hotel Sacher, established by Eduard in 1876. Since then, the cake remains among the most famous of Vienna's culinary specialties.