Prepare the raspberry filling: Place the raspberries, sugar, and 100 ml of the water in a medium saucepan. Cook over low heat, stirring occasionally, until the raspberries soften and the mixture begins to simmer.
Thicken the raspberry filling: In a small bowl, whisk the remaining 100 ml of water with the cornstarch until completely smooth. Slowly pour it into the simmering raspberries while stirring continuously. Cook until the filling becomes thick and glossy. Remove it from the heat and allow it to cool completely. Reserve a small amount for decorating the ganache.
Prepare the gelatin: Sprinkle the gelatin over 3 tablespoons (45 ml) of cold water and leave it to bloom for approximately 10 minutes. Gently melt the bloomed gelatin in the microwave for a few seconds. It should be fully dissolved but must not boil.
Whip the heavy cream: Beat the cold heavy whipping cream in a large bowl until medium-stiff peaks form. Be careful not to overwhip it; the cream should remain smooth, light, and fluffy.
Prepare the cream cheese mixture: In a separate bowl, beat the softened cream cheese, sweetened condensed milk, and vanilla extract until smooth and creamy.
Combine the filling: Add the whipped cream to the cream cheese mixture and gently mix until evenly combined.
Add the gelatin: Stir a few spoonfuls of the cream cheese filling into the melted gelatin. Pour this mixture back into the remaining filling and mix immediately until the gelatin is completely incorporated.
Prepare the cake ring: Place a 9 1/2-inch (24 cm) cake ring on a flat serving plate or cake board. Line the inside with an acetate cake collar, then place the thin vanilla sponge cake layer on the bottom.
Add the first cheesecake layer: Spread half of the cream cheese filling evenly over the vanilla sponge cake. Smooth the surface with an offset spatula.
Add the raspberry layer: Carefully spread the cooled raspberry filling over the cheesecake layer. Remember to reserve a small amount for decorating the top.
Add the remaining filling: Carefully spoon the remaining cream cheese filling over the raspberry layer. Spread it gently to keep the layers separate, then smooth the surface. Refrigerate the No-Bake Raspberry Cheesecake for approximately 30 minutes.
Prepare the white chocolate ganache: Place the chopped white chocolate and heavy whipping cream in a microwave-safe bowl. Heat in short intervals, stirring after each one, until the chocolate is melted and the ganache is completely smooth. Allow it to cool slightly.
Decorate the ganache: Pour the ganache over the chilled cheesecake and spread it evenly. Add small dots of the reserved raspberry filling across the surface. Drag the tip of a knife or toothpick through the dots to create a decorative pattern.
Chill the cheesecake: Return the cheesecake to the refrigerator and chill for at least 6-8 hours, preferably overnight, until completely set.
Remove and decorate: Carefully remove the cake ring and peel away the acetate collar. Decorate the cheesecake with piped whipped cream and freeze-dried raspberries.
Slice and serve: Serve the cheesecake well chilled. For clean slices, dip a sharp knife in hot water, wipe it dry, and repeat before every cut.