Rich mocha filling
Chocolate butter cream
1.Preheat oven to 180°C (160°C fan-forced). Grease deep 22cm-round cake pan; line base with baking paper.
2.Stand liqueur and rind in small bowl for 30 minutes. Strain; reserve rind and liqueur separately.
3.Combine chocolate, butter and rind in large bowl. Stir in 3 teaspoons of the liqueur, egg yolks and sifted flour.
4.Beat egg whites in large bowl with electric mixer until soft peaks form; gradually add sugar, beating until dissolved between additions. Fold whites into chocolate mixture, in two batches.
5.Pour mixture into pan; bake about 35 minutes. Stand cake in pan 5 minutes before turning, top-side up, onto wire rack to cool.
6.Meanwhile, make rich mocha filling. Combine coffee and the water in large bowl; stir in melted chocolate, then yolks and ⅓ cup of the remaining liqueur. Refrigerate until set.
7.Next make chocolate butter cream. Combine coffee and the water in large bowl; stir in the chocolate and remaining liqueur. Beat yolks and sugar in small bowl with electric mixer until thick and creamy; beat in butter in several batches until smooth.
8.Gradually beat in chocolate mixture; refrigerate 10 minutes or until spreadable.
9.Split cake into three layers. Place first layer on serving plate; spread with half the mocha filling. Refrigerate 15 minutes. Top with second layer; spread with remaining mocha filling. Top with third layer; refrigerate 30 minutes.
10.Spread butter cream over top and side of cake; refrigerate 30 minutes.