In a heavy saucepan heat the milk on medium high heat to bring it to a gentle boil.
While the milk is heating, in a separate bowl mix the egg yolks, egg, sugar, salt, rosewater and the starch with a whisk until you have a creamy substance. Set aside until the milk has come to a gentle boil.
While whisking constantly, slowly drizzle the hot milk into the egg mixture. Be sure to take your time as you slowly drizzle the hot milk while whisking the eggs to properly temper the eggs and not cook them into scrambled eggs.
Return the mixture back into the saucepan and continue to whisk constantly over medium heat for 1-2 minutes or until the custard begins to thicken.
Continue to whisk until the custard comes back to a gentle boil and starts bubbling.
Reduce heat at the sight of the first bubbles and continue to cook on low heat for another minute to two.
Remove custard from the heat and add butter and continue to whisk until the mixture is glistening and butter has fully been integrated into the custard.
Pour the custard into a shallow container and place plastic wrap directly on the surface of the custard. This will prevent a skin from forming on the custard surface.
Refrigerate the custard until fully chilled before using.
Place the heavy cream, sugar and vanilla in a large chilled bowl. Using an electric mixer, whisk the mixture on medium speed until the sugar has dissolved and the mixture begin to form a soft peak.
Increase the speed and continue to whisk until you have formed a stiff peak.
Place the whipped cream back in the refrigerator until ready to use.
Preheat oven to 400° F.
Thaw out the puff pastry at room temperature for about half an hour.
Divide the puff pastry sheet into 9 equal squares. Alternatively, you can use your favorite cookie cutter to cut out various shapes and sizes.
Line a baking tray with parchment paper and arrange the puff pastry on the tray. Be sure to leave about an inch of space between the pieces.
Depending on the size of your pastries, bake them for 15 to 20 minutes or until fully puffed and golden and crispy.
Remove from the oven and allow to cool to room temperature before assembly.
Using your fingers, crumble one puff pastry square to use as topping. Set aside.
Using a serrated knife, carefully cut the remaining pieces in half horizontally.
Using a spoon or spatula, place equal amounts of the creme patissiere on the bottom half of the pastries.
Carefully place the top pieces of the pastries on top of the creme patissiere.
Spread or pipe an equal amount of the whipped cream on top of each piece and sprinkle the crushed puff pastry, ground pistachios and confectioners sugar on top.
Place on a serving platter and chill before serving.
Store the Shirini Napoleoni in an airtight container in the refrigerator.