6 ounces bittersweet chocolate, chopped (such as Valrhona)
1/4 cup unsalted butter, cut into small pieces
1/4 cup light corn syrup
1/4 cup crème de cassis
For truffle cream:
Stir chocolate, cream and butter in heavy saucepan, over low heat until chocolate and butter melt and mixture are smooth. Mix in liqueur. Let stand at room temperature until very thick and spreadable, stirring occasionally, about two hours.
Preheat oven to 350 degrees. Butter 9-inch heart-shaped pan with 1 1/4-inch high sides. Dust with flour. Sift first four ingredients into bowl. At high speed beat sugar and butter until fluffy. Add yolks one at a time, beating just to combine after each addition.
With rubber spatula, mix in dry ingredients alternately with buttermilk, beginning and ending with dry ingredients.
Transfer batter to prepared pan. Bake until tester inserted in center comes out clean, about thirty five minutes. Turn out onto rack and cool. Cut cake horizontally in half. Spread truffle cream over bottom layer. Arrange top layer over and press gently. Smooth cream on sides of cake if necessary. Chill at least one hour.
Stir chocolate and butter in saucepan over low heat until melted and smooth. Remove from heat. Add corn syrup and liqueur and whisk until smooth. Let glaze stand until lightly thickened, stirring occasionally, about thirty minutes.
Place cake on rack. Pour glaze over cake, coating completely. Chill cake on rack until glaze is set, about thirty minutes.
Transfer cake to platter. Garnish with raspberries.