Preparation Steps

• Line a 9-inch springform pan with a parchment round and, if you have one, a cake collar around the sides. Place a metal mixing bowl and whisk attachment in the refrigerator to chill while you start the fillings.
• For the raspberry base: Puree 3/4 cup raspberries in a mini processor and press through a fine sieve to yield about 1/4 cup seedless puree. Sprinkle 1 1/2 teaspoons gelatin over 1 tablespoon cold water; let stand 5 minutes. Warm the raspberry puree in a small saucepan just until steamy, then whisk in the bloomed gelatin until fully dissolved. Set aside to cool to room temperature. Separately, heat 1/4 cup cream until hot (do not boil) and pour over 4 ounces chopped white chocolate; rest 2 minutes, then whisk smooth. Let both mixtures cool until barely warm.
• Make the crust: Pulse the chocolate sandwich cookies into fine crumbs. Stir in the melted butter and a pinch of sea salt until evenly moistened. Press firmly into the bottom and 1 1/2 inches up the sides of the prepared pan. Freeze for 15 minutes to set.
• Start the chocolate ganache base: Bloom 1 1/4 teaspoons gelatin in 1 tablespoon cold water for 5 minutes. Warm 1/4 cup cream until steaming, whisk in 1 tablespoon cocoa powder and the bloomed gelatin until dissolved. Pour this over 4 ounces chopped dark chocolate; let sit 2 minutes, then whisk until silky. Stir in the vanilla and let cool to lukewarm.
• Chocolate mousse: Beat 8 ounces cream cheese with 1/3 cup granulated sugar and the remaining 2 tablespoons cocoa until light and smooth. Beat in the cooled dark chocolate mixture. In the chilled bowl, whip 3/4 cup cream with 3 tablespoons powdered sugar to medium peaks; fold into the chocolate base in two additions. Spread into the cold crust and tap the pan gently to level. Refrigerate 20–30 minutes to begin setting.
• Raspberry–white chocolate mousse: In a clean bowl, beat 8 ounces cream cheese with 1/3 cup granulated sugar and lemon zest until creamy. Mix in the cooled raspberry–gelatin puree, then the cooled white chocolate mixture until fully combined. Whip 3/4 cup cream with 2 tablespoons powdered sugar to medium peaks and fold into the raspberry base. Gently fold in the remaining 1/2 cup raspberries (halved). Spoon over the chocolate layer and smooth the top.
• Chill the assembled cake, covered, for at least 4 hours or until the layers are sliceably firm. Overnight is ideal for the cleanest cuts.
• Finishing: Unmold the cake and transfer to a serving plate. Whip 3/4 cup cream with 2 tablespoons powdered sugar and 1/2 teaspoon vanilla to medium-firm peaks; pipe rosettes around the edge. For an easy drizzle, heat 1/4 cup cream until hot and pour over 2 ounces chopped dark chocolate; rest 1 minute, then whisk smooth and cool briefly. Drizzle over the cake and rosettes.
• Practical tip: For ultra-clean slices, dip a large knife in hot water, wipe it dry, and cut straight down—reheat and wipe the blade between each slice.