Ingredients
Equipment
Method
Step 1: Whisk the Genoise to Ribbon Stage
Preheat your oven to 350°F (175°C). Line the bottom of your 8-inch springform pan with parchment paper, leaving the sides ungreased (the sponge needs to grip the bare metal walls to climb). In your stand mixer, whip the 4 room-temperature eggs and granulated sugar on high speed for precisely 7 to 8 minutes. The mixture will triple in volume, turning pale ivory. When you lift the whisk, the batter should fall back onto itself in thick, slowly dissolving ribbons.Step 2: Sift, Fold, and Bake
In a separate bowl, whisk together the flour, potato starch, and baking powder. Sift this dry mixture over the egg foam in three separate batches. Using a wide rubber spatula, fold the dry ingredients in with an extremely gentle, scooping motion—plunging down the center and sweeping up the side of the bowl. Pour the aerated batter into your pan and bake for 30 to 35 minutes until the center springs back to a light touch. Cool upside down on a wire rack to keep the sponge from sinking, then slice horizontally into three uniform discs. Scaling tip: If you are baking for a smaller household, apply the pan conversions found in our small-batch baking handbook.Step 3: Cook the Velvet Vanilla Custard
In your heavy saucepan, warm the milk, cream, and scraped vanilla bean over medium heat just until steam rises. In a separate bowl, whisk the egg yolks, sugar, and cornstarch until smooth. While whisking the egg mixture vigorously, slowly drizzle in half a cup of the hot milk to temper the yolks. Pour the warmed yolks back into the saucepan with the rest of the milk. Cook over medium heat, whisking constantly, until the custard begins to bubble and turns into a thick, glossy pudding. Pass it through a fine-mesh strainer into a bowl, press a sheet of plastic wrap directly onto the surface to prevent a skin from forming, and chill completely.Step 4: Whip the Cream to Peak Stability
Pour your cold heavy cream into a chilled stainless steel bowl. Add one tablespoon of powdered sugar. Whip on medium-high speed until firm, stiff peaks form. Crucial warning: You need the cream to be stiff enough to hold its shape like wet clay, but stop beating the second it loses its glossy sheen, or it will churn into sweet butter. Reserve one cup of this whipped cream for the thin "crumb coat," leaving the bulk of it for the center dome.Step 5: Construct the Foundation Layers
Place your bottom genoise layer onto a flat serving platter. Spread the seedless raspberry jam across the sponge, leaving a 1/4-inch border around the perimeter. Next, take your chilled vanilla custard and spoon it gently over the jam, smoothing it into a flat, level disc. Place your second genoise sponge layer directly on top of the custard, pressing down with bare, feather-light pressure to lock the tiers together.Step 6: Sculpt the Signature Cream Dome
Pile the large mound of reserved whipped cream directly into the center of the second sponge tier. Using your offset spatula, sculpt the cream into a smooth, high, rounded hemisphere—thick in the dead center and tapering down to a whisper at the outer edges. Take your third and final sponge tier and place it dead-center on top of the cream mound. Using your cupped, open palms, gently press and mold the sponge downward so it hugs the cream, creating a smooth, rounded green-hill contour. Spackle the entire exterior of the dome with your reserved cup of whipped cream to lock the crumbs in. Chill the naked dome for 30 minutes.Step 7: Drape the Marzipan Blanket
Dust your silicone mat lightly with powdered sugar. Roll your green marzipan out into a large 14-inch circle, roughly 1/8-inch thick. Carefully lift the marzipan sheet over your rolling pin and drape it centered over the chilled cream dome. Using the sides of your hands, gently smooth the marzipan from the top dead center down the curves. To prevent folds or pleats around the bottom edges, gently "lift and fan" the marzipan skirt outward with one hand while smoothing it flush against the cake base with your other hand.Step 8: The Royal Finish
Take a sharp pizza cutter or paring knife and trim the excess marzipan flush against the bottom of the cake platter. Using a fine tea strainer, dust the top hemisphere with a light, snowy layer of powdered sugar. Finally, place your pink marzipan rose directly in the center of the dome.