Swedish Princess Cake

Instructions

1. Prepare the sponge cake
   Preheat oven to 180°C (350°F). Grease and line a 23cm (9-inch) springform pan. In a large bowl, beat eggs and sugar until pale and tripled in volume, about 5-7 minutes. Sift flour and baking powder together, then gently fold into egg mixture. Finally, fold in melted butter. Pour into prepared pan and bake for 25-30 minutes until golden and springy to touch. Cool completely on a wire rack.
2. Make the vanilla custard
   In a saucepan, bring milk and vanilla seeds to a simmer. In a separate bowl, whisk egg yolks, sugar, and cornstarch until pale. Gradually pour hot milk into egg mixture, whisking constantly. Return mixture to saucepan and cook over medium heat, stirring continuously, until thickened. Transfer to a bowl, cover surface directly with plastic wrap to prevent skin forming, and refrigerate until cold, at least 2 hours.
3. Assemble the base layers
   Cut the cooled sponge horizontally into three even layers. Place the bottom layer on a cake board or serving plate. Spread with half the raspberry jam. Whip 300ml (1 1/4 cups) of the heavy cream until soft peaks form, then fold half into the chilled custard. Spread half the custard cream over the jam. Top with the middle sponge layer and repeat with remaining jam and custard cream.
4. Create the dome shape
   Place the final sponge layer on top. Whip the remaining 300ml cream until stiff peaks form. Pile most of it on top of the cake and use a palette knife to create a dome shape, leaving a small amount of cream for touch-ups. Refrigerate for 30 minutes to set.
5. Apply the marzipan covering
   Dust a work surface with powdered sugar. Roll out the green marzipan into a large circle, about 40cm (16 inches) in diameter and 3-4mm thick. Carefully lift the marzipan over the cake and gently smooth it down over the dome, trimming excess at the bottom. Use your hands to smooth out any wrinkles or air bubbles.
6. Finish and decorate
   Dust the cake lightly with powdered sugar. If using, place a marzipan rose on top. Trim any excess marzipan from the base for a neat finish. Refrigerate for at least 2 hours before serving to allow all layers to set properly.