Sponge

1. Preheat oven to 350°F. (175°C) Grease and line the bottom of a 9-inch (24 cm) springform pan with parchment paper.

2. In a large bowl, whip eggs and sugar with an electric mixer on high speed for 5–7 minutes, until very light, pale, and airy.

3. Sift together the all-purpose flour and potato flour. Gently fold into the egg mixture in two additions, taking care not to deflate the batter.

4. Stir in the vanilla paste just until incorporated.

5. Pour batter into the prepared pan and bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.

6. Let cool for 10 minutes in the pan, then invert onto a wire rack to cool completely.

7. Once cooled, slice horizontally into three even layers.

Vanilla Cream

1. In a saucepan, heat the milk over medium heat until just steaming.

2. In a bowl, whisk together egg yolks, sugar, cornstarch, and vanilla paste until smooth.

3. Slowly pour the hot milk into the egg mixture while whisking constantly.

4. Return the mixture to the saucepan and cook over medium heat, whisking continuously until thickened and starting to bubble.

5. Remove from heat, transfer to a clean bowl, and cover the surface directly with plastic wrap. Let the plastic touch the surface of the cream to avoid skin forming on top. Let cool completely.

6. Once cooled, fold in the whipped cream to make a light vanilla cream (crème diplomat style).

Filling & Assembly

1. Prepare the bowl: Choose a medium-sized rounded bowl (about 2 L capacity). Lightly dust the entire inside of the bowl with powdered sugar — this prevents the marzipan from sticking and gives a smooth, matte finish once unmolded.

2. Line with marzipan: Roll the green marzipan on a powdered sugar–dusted surface until it’s about 2–3 mm thick and large enough to fully cover the inside of the bowl. Gently lift and press the marzipan into the bowl, smoothing out any folds or bubbles. Let the excess hang slightly over the rim — you’ll trim it later.

3. Add whipped cream layer: Spread a thick, even layer of whipped cream (about 1 inch) directly over the marzipan, pressing gently with a spatula to eliminate air pockets. This forms the cake’s outer dome once flipped.

4. Add vanilla cream: Spoon the vanilla cream over the whipped cream and smooth evenly to create a creamy inner layer.

5. Add sponge and filling layers: Place one sponge cake layer on top of the vanilla cream. Spread a thin layer of raspberry jam over the sponge. Add a thin layer of whipped cream, then another sponge layer. Repeat with a little more whipped cream if needed, and finish with the final sponge layer as the base.

6.  Chill to set: Gently press down to compact the layers slightly, then refrigerate the cake for at least 4 hours, or overnight, to firm up and hold its shape.

7. Unmold the cake: Place your serving plate over the bowl and invert the cake in one smooth motion. Lift off the bowl carefully — the marzipan should release cleanly thanks to the powdered sugar dusting.

8. Finish: Trim any excess marzipan around the base.

9. Dust lightly with powdered sugar and top with a marzipan rose or decorative flourish.