Raspberry Sauce: In food processor or blender, puree raspberries and icing sugar.
Strain. Stir in liqueur. (Sauce can be refrigerated for up to 3 days.)
Custard: In large saucepan, heat milk and cream until hot.
In bowl, beat eggs
with sugar until light, about 3 minutes; whisk in flour until smooth. Pour in hot
milk mixture, whisking constantly. Return to pan; cook, whisking constantly, until
boiling. Stir in liqueur; simmer, whisking, for 2 minutes.
Stir in vanilla extract.
Pour into bowl; place plastic wrap directly on surface and let cool to room temperature.
(Custard can be refrigerated for up to 8 hours.)
Chocolate Truffle Sauce: In top of double boiler over simmering water, melt chocolate,
cream and liqueur, stirring. Let cool to room temperature.
Assembly: Cut cake into 3 layers. Drizzle 1/2 cup Raspberry Sauce over bottom
and sides of serving bowl. Place 1 cake layer on bottom; drizzle with 2 tbsp of
the liqueur. Pour one-third of Custard over cake. Drizzle with one-third remaining
Raspberry Sauce. Reserve 3 tablespoons Chocolate Truffle Sauce for garnish; drizzle
with one-third remaining Chocolate Truffle Sauce. Repeat with two more layers of
cake, liqueur, custard and sauces. Refrigerate for at least 8 hours or up to 1 day.
Whip cream; add remaining liqueur. Spread over top.
Warm reserved Chocolate Truffle Sauce slightly; drizzle with fork over whipped cream.