Prepare the pistachio cream by blending the pistachios in a food processor until very smooth, stopping to scrape down the sides as needed. Add the melted white chocolate and neutral oil, then continue blending until the mixture becomes creamy and spreadable. Taste and add confectioners' sugar if you want it sweeter. Set aside.
1½ cups (180 g) unsalted, shelled pistachios, 3 oz (85 g) white chocolate, 1½ tbsps (22 ml) neutral oil, 1½-3 tbsps (12-24 g) confectioners' sugar
In a shallow bowl, combine the cooled coffee, sugar, and vanilla extract, stirring until the sugar is dissolved. Set aside.
2¼ cups (540 ml) strongly brewed coffee or espresso, 3-4 tbsps (38-50 g) granulated sugar, 1½ tsps (7 ml) vanilla extract
In a large bowl, mix the cold mascarpone, confectioners' sugar, and vanilla extract until smooth and fully combined. In a separate bowl, whip the heavy cream to stiff peaks. Gently fold the whipped cream into the mascarpone mixture until light and uniform, being careful not to deflate the mixture.
24 oz (680 g) mascarpone cheese, 1⅛ cups (140 g) confectioners' sugar, 1½ tsps (7 ml) vanilla extract, 3 cups (720 ml) heavy whipping cream
Working in a 9x13-inch (23x33 cm) dish, quickly dip each ladyfinger into the coffee mixture and arrange in a single layer, covering the bottom of the dish. Spread half of the mascarpone filling evenly over the ladyfingers, reaching all the way to the edges. Spoon a thin, even layer of pistachio cream over the mascarpone.
1½ packages (~300-350 g) ladyfingers cookies, 1⅛ to 1½ cups (270-360 g) pistachio cream
Add a second layer of dipped ladyfingers, arranging them tightly to fully cover the surface. Spread the remaining mascarpone filling evenly over the top. Finish with another thin layer of pistachio cream, smoothing gently or lightly swirling for a marbled effect.
Cover the dish and refrigerate for at least 6 hours or overnight to allow the layers to set and the flavors to develop.
For the topping, whip the heavy cream, confectioners' sugar, vanilla extract, and cornstarch to stiff peaks. Use a piping bag with a large round tip and hold it straight up and down to pipe the whipped cream in soft, rounded mounds across the top, working in rows so the surface is fully covered without flattening it. You can also just spread the whipped cream over the top if you don't want to pipe it. Drizzle lightly with additional pistachio cream and finish with finely chopped pistachios before serving.
3 cups (720 ml) heavy whipping cream, 6 tbsps (45 g) confectioners' sugar, 1½ tsps (7 ml) vanilla extract, 1½ tsps (4 g) cornstarch, 6 tbsps (45 g) unsalted, shelled pistachios, extra pistachio cream