Baklava dome cake

Method

1. Heat the oven to 180°C/ 160°C fan/gas 4. Grease and line the sandwich tins. Put all the ingredients for the sponges (except the walnuts) in a large mixing bowl and use an electric mixer to whisk everything together. You want the batter to be smooth and lump-free. Gently stir in the whizzed walnuts.
2. Divide the mixture equally between the 2 tins, then put them both in the oven to bake for 20-25 minutes or until golden brown and the sponges spring back when touched. Leave to cool completely.
3. Meanwhile, make the raspberry cream. Put the raspberries, rosewater and icing sugar in a small blender and whizz to a purée. Pass through a fine sieve into a bowl to remove the seeds. Whip the cream to soft peaks (which flop over when you remove the whisk), then stir in the raspberry purée. Keep in the fridge until needed.
4. To make the pistachio icing, add all the ingredients to a large bowl and use an electric mixer to beat the mixture for 2 minutes until smooth. Divide the mixture between 2 bowls and set aside.
5. Line a 20cm pyrex or mixing bowl with cling film so it overhangs the edges. Using a plate as a guide, cut one of the sponges down into an 18cm circle. Use the offcuts to create a smaller round cake, about 10cm in diameter. It doesn’t matter if this circle is imperfect or a bit messy. You should now have 3 sponges – a full 20cm one, an 18cm one and a 10cm one (which will be a bit raggedy compared to the other two).
6. Halve the sponges horizontally, then stick them back together by spreading# with a good layer of pistachio cream, followed by the chilled raspberry cream. (Use the creams to ‘glue’ the smallest sponge into a rough circle.)
7. Put the smallest sponge in the base of the bowl, then take 1 bowl of the pistachio icing and spread roughly half of it over the top, filling any gaps between the sponge and the bowl. Put the 18cm sponge on top, spread the exposed base with the raspberry jam, then add the remaining pistachio icing. Finally, put the largest 20cm sponge on top, pressing everything down so the base is firm and flat. Leave to set in the fridge for an hour.
8. When ready to decorate, remove the cake from the fridge and turn out onto a serving plate, using the cling film to help you. Take the second bowl of pistachio icing and use most of it to cover the cake, creating a smooth dome shape. Put the remaining icing into 2 piping bags with different nozzles (see Specialist Kit). Pipe the icing however you like (we made short snaking patterns, alternating with our 2 nozzles), then finish with rose petals and pistachios.