Frozen tiramisu terrine

Ingredients

• 4 egg yolks
• 2 eggs
• 1/2 cup (110g) caster sugar
• 300 millilitre cream
• 250 gram mascarpone cheese
• 2 tablespoon marsala
• 450 gram packet rectangular unfilled sponge slabs
• 1 tablespoon instant coffee granules
• 2 tablespoon boiling water
• 100 gram dark eating chocolate, grated coarsely
• 100 gram dark eating chocolate, chopped finely
• 1/3 cup (80ml) cream