In heavy saucepan, combine chocolate and butter. Cook and stir oer low heat until chocolate melts. Remove from heat. Stir in sugar, flour, and 1 tsp. raspberry liquer, if desired. With wooden spoon, beat in yolks, 1 at a time, just until combined; set aside. In large bowl beat egg whites with electric mixer on high speed until stiff peaks form. Fold in chocolate mixture. Pour into greased 8 inch springform pan. Bake in 350F oven 25 to 30 minutes or until edges puff. Cool on rack 30 minutes. Remove sides of pan; cool. Chill, covered, 4 to 24 hours.
To serve, top with Sweetened Whipped Cream, raspberries, and Chocolate Curls. Drizzle each piece with 1 tbls. melted jam. Serves 12. Sweetened Whipped Cream: Chill mixing bowl and beaters of electric mixer in refrigerator. In chilled bowl combine 1 cup whipping cream, 2 tbls. powdered sugar, and 1/2 tsp. vanilla. Beat with chilled beaters on medium speed until soft peaks form. Makes 2 cups. Chocolate Curls: Draw vegetable peeler across bar of chocolate. Transfer curls to top of cake with toothpick or wooden skewer.