In small bowl, mix all sauce ingredients. Cover; refrigerate until serving time.
In 1-quart saucepan, heat chocolate over low heat, stirring occasionally, just until melted. Remove from heat. Stir in 1/4 cup of the whipping cream.
In medium bowl, beat remaining 3/4 cup whipping cream with electric mixer on high speed until stiff peaks form. Beat in chocolate mixture and amaretto. Serve immediately, or cover and refrigerate up to 2 hours.
To serve, cut cake into 8 slices; place on individual dessert plates. Spoon about 1/3 cup sauce over each slice. Top each with about 1/4 cup chocolate cream mixture; drizzle with 1 teaspoon chocolate syrup.