Chocolate Orange Tiramisu Cake

Ingredients

• For the orange filling:
• 300 ml orange juice
• 60 g sugar
• 20 g cornstarch
• For the chocolate sponge:
• 2 eggs
• 1 pinch salt
• 190 g sugar
• 95 g vegetable oil
• 90 g milk
• 95 g sour cream
• 190 g plain flour
• 40 g unsweetened cocoa powder
• 3.5 g baking powder
• 4 g baking soda
• For the coffee mixture:
• 2 tsp instant coffee
• 90 ml hot water
• For the mascarpone cream:
• 300 ml cold whipping cream, 32–35% fat
• 90 g icing sugar
• 300 g mascarpone
• For assembly and decoration:
• 250 g Savoiardi biscuits
• 1–2 tsp cocoa powder, for dusting
• 60 g chocolate
• 7 g vegetable oil

Method

1. For the orange filling, whisk the orange juice, 60 g sugar and 20 g cornstarch together in a saucepan until smooth.
2. Cook over medium heat, stirring continuously, until the mixture boils and thickens. Continue cooking for 1–2 minutes, then transfer it to a bowl and leave it to cool completely.
3. Preheat the oven to 170°C. Grease and line an 18 cm round cake tin.
4. For the sponge, whisk the eggs, salt and 190 g sugar until pale, thick and fluffy.
5. Mix in the vegetable oil, milk and sour cream.
6. Sift together the flour, cocoa powder, baking powder and baking soda. Fold the dry ingredients gradually into the egg mixture.
7. Dissolve the instant coffee in 90 ml hot water. Mix approximately half of the coffee into the chocolate batter and reserve the remainder for dipping the Savoiardi.
8. Pour the batter into the prepared tin and bake for 40–45 minutes. Check that a skewer inserted into the centre comes out clean, then cool the sponge completely.
9. For the mascarpone cream, whip the cold cream with the icing sugar until it begins to thicken. Add the mascarpone and continue mixing just until the cream is thick and smooth.
10. Level the cooled chocolate sponge if necessary and return it to a clean 18 cm cake ring or springform tin.
11. Spread a layer of mascarpone cream over the sponge, followed by the cooled orange filling.
12. Briefly dip the Savoiardi in the reserved coffee and arrange them closely over the filling.
13. Cover the Savoiardi with more mascarpone cream, reserving enough cream to finish the outside of the cake.
14. Cover and refrigerate the assembled cake for 4–6 hours, or until firm.
15. Remove the chilled cake carefully from the tin and smooth the remaining mascarpone cream over its top and sides.
16. Melt the chocolate with 7 g vegetable oil over a water bath or in short microwave bursts. Allow it to cool slightly, then use it to decorate the cake.
17. Dust with cocoa powder and keep refrigerated until ready to serve.