For filling: Add heavy cream, mascarpone, vanilla bean paste, and salt to a saucepan; heat over medium-low heat until warm, about 5 minutes. Add white chocolate, and whisk until fully melted.
Pour mixture into a large mixing bowl and cover with plastic wrap. Place the bowl in the refrigerator for at least 6 hours, ideally overnight. While the cream is cooling, make the ladyfingers.
Preheat the oven to 350°F (180°C).
For ladyfingers: In a small bowl, whisk together flour, cornstarch, and salt. In a separate bowl, separate the egg whites and egg yolks.
In the bowl of a stand mixer fitted with the whisk attachment, add egg whites and beat at medium speed until bubbly; then begin to slowly add 1⁄3 cup (67 grams) granulated sugar with the mixer going. Mix until stiff peaks form and then place the meringue into a clean mixing bowl.
Clean the bowl of the stand mixer and whisk attachment and reattach to the mixer. Add egg yolks and remaining 1⁄3 cup (67 grams) granulated sugar and beat at medium speed for 3 to 4 minutes until pale yellow and slightly thickened in texture. Gently fold the meringue into the egg yolks and then fold in the flour/ cornstarch mixture.
Add the batter to a piping bag with a 1⁄2-inch round tip.
Line two baking sheets with parchment paper and pipe 3x1-inch ladyfingers onto the baking sheet, spacing each about 1 inch apart.
Add confectioners’ sugar to a fine-mesh sieve and dust the ladyfingers with a generous amount of the sugar.
Bake for 8 to 12 minutes until golden brown and dry. Set aside to cool completely.
Remove the cream mixture from the refrigerator and pour into a stand mixer fitted with the whisk attachment. Beat at medium speed for 3 to 5 minutes until thick and fluffy—do not overmix! As soon as stiff peaks form, stop mixing.
Remove two-thirds of the cream into a mixing bowl. Add raspberry preserves and extract if using, and mix together until just combined.
In a small mixing bowl, add almond liqueur.
Spread plain cream into the bottom of a 13x9-inch or 3-quart serving dish. Dip ladyfingers, one at a time, into the liqueur. Fit as many ladyfingers into a single layer as possible, about 20 ladyfingers. Spread half of the raspberry cream (about 2½ cups/419 grams) on top of the ladyfingers and then repeat dipping the remaining ladyfingers into the liqueur and place on top of the raspberry cream in a single layer. Add the remaining raspberry cream on top and dust with cocoa powder. Place in the refrigerator for at least 6 hours, ideally overnight.
Just before serving, garnish with shaved white chocolate and raspberries, if desired.