Requires: 1.5 litre pudding bowl (alternatively a round bowl), electric mixer (or hand beater)
To make the ricotta firm in preparation for the filling, drain in a colander for a few hours to overnight.
Note: Steps 1-10 to be completed 1 day ahead
Preheat oven to 180°C conventional oven (400° Fahrenheit/Gas 6). Grease a 30cm round cake pan by lightly buttering the base and sides with margarine or butter. Line the base with baking paper, then lightly butter over the baking paper. Add a tablespoon of 00 flour, then turn and shake the tin to coat the butter in flour on the base and sides of the cake pan.
To make the Italian sponge cake, use an electric mixer or hand beater to beat the egg whites with a pinch of fine sea salt until stiff peaks form. With the mixer (or hand beater) running, add the egg yolks, one at a time. Add the sugar, one tablespoon at a time, beating well after each addition. Use a wooden spoon to stir in the cornflour, one tablespoon at a time. You want to see air bubbles rise to the surface of the cake mixture before adding additional tablespoons of cornflour. Stir the sifted baking powder, then add the lemon zest and stir until well combined. Pour the cake mixture into the prepared cake pan.
Bake the Pan di Spagna for 25 mins or until a skewer inserted in centre comes out clean. Allow to cool in the cake pan for 10 minutes, then transfer to a wire rack to cool completely.
Meanwhile, to make the alchermes syrup, combine the water, alchermes and sugar in a small saucepan over low-medium heat. Bring to the boil, then remove from the heat. Set aside to cool.
Place the thickened cream in a bowl. Use an electric mixer or hand beater to beat until stiff peaks form. Refrigerate until ready to use.
To make the ricotta filling, whisk the ricotta, orange zest and 100g of the caster sugar until smooth. Set aside 30g of the caster sugar for the chocolate mousse filling. Whisk in 1/3 of the thickened cream into the ricotta mixture until combined. Add 1/3 (50g) of the dark chocolate bits and 100g candied orange/lemon peel (optional) to the ricotta filling. Stir to combine. Refrigerate until ready to use.
To make the chocolate mousse filling, heat the remaining chocolate and remaining 30g caster sugar in a heat-resistant bowl over a saucepan of gently simmering water. Stir with a metal spoon over low heat for 2-3 mins or until completely melted. Remove from the heat. Whisk the thickened cream through the chocolate mixture, one heaped spoon at a time until well combined and smooth.
To make the zuccotto, line a 1.5 litre pudding bowl (or round bowl) with plastic wrap, allowing the plastic wrap to hang over the edge of the bowl. Cut the Pan di Spagna into 1.5cm slices. Arrange the Pan di Spagna slices tightly inside the entire bowl, trimming any excess and leaving no gaps. Using a pastry brush, generously soak the sponge using 2/3 of the alchermes syrup.
Spoon the ricotta mixture into the cake-lined bowl. Use the back of a spoon to make a well in the centre of the zuccotto. Spoon the chocolate mousse filling into the well. Top with cake layers to tightly cover the top of the bowl. Brush the top of the sponge layer using the remaining alchermes syrup. Cover the Zuccotto with the overhanging plastic wrap and top with a flat plate. Place a heavy can on top of the plate and place in the fridge to set overnight.
To serve, turn the zuccotto onto a serving plate. Remove and discard the plastic wrap. Dust the top of the zuccotto with unsweetened cocoa powder (cacao magro). Cut into 8 wedges to serve – buon appetito.