Black Forest trifle

Name: Black Forest trifle
Prep time: 3 h 20 min
Cook time: 14 min
Total time: 3 h 34 min
Cuisine: European, German, British
Ingredients: 20.00 gm cornflour; 125ml cherry; 75g caster sugar; 80ml kirsch; 300ml thickened cream; 24.00 gm icing sugar, sifted; 1 chocolate cake (see Notes), chilled; Grated chocolate, to garnish; 160ml milk; 200ml pure (thin) cream; 3 egg yolks; 40.00 gm caster sugar; 40.00 ml cherry jam