8. In a separate bowl, whip the heavy cream and powdered sugar together until stiff peaks form.
9. To assemble the cake, place one cake layer on a serving plate. Spread a layer of whipped cream on top, followed by a layer of crushed pineapple. Place the second cake layer on top.
10. Frost the top and sides of the cake with the remaining whipped cream. If desired, garnish with additional crushed pistachios.
11. Refrigerate the cake for at least one hour before serving to allow the flavors to meld together.