In a mixing bowl, combine the crushed vanilla wafers, granulated sugar, salt, and melted unsalted butter. Mix until the crumbs are evenly coated and resemble wet sand. Press this mixture firmly into the bottom and sides of an 8-inch or 9-inch springform pan, creating an even layer. Chill the crust in the refrigerator for 30 minutes to firm up before adding the filling.

In a separate mixing bowl, beat the room temperature cream cheese with an electric hand mixer until smooth and creamy. Gradually add the instant pistachio pudding mix, vanilla extract, pistachio extract, and powdered sugar, mixing until well combined. Slowly pour in the heavy cream, beating until the filling becomes light, fluffy, and holds soft peaks. Spoon the filling into the chilled crust, smoothing the top with an offset spatula.

Cover the filled springform pan with plastic wrap and place it in the refrigerator. Chill the cheesecake for at least 6 hours, but overnight is ideal.

Just before serving, whip heavy cream in a mixing bowl with powdered sugar and vanilla extract using a hand mixer or stand mixer. Beat until stiff peaks form.

Once the cheesecake is chilled and firm, remove it from the springform pan. Spread or pipe the whipped cream topping over the surface of the cheesecake and sprinkle with chopped pistachios before serving.

Slice the cheesecake into wedges and serve chilled, garnish with extra pistachios or a dollop of whipped cream.