Preheat oven to 400°F (200°C) and line two large baking sheets with parchment paper.

Roll out thawed puff pastry sheets on a lightly floured surface until about ⅛ inch thick.

Transfer pastry sheets to prepared baking sheets, brush with melted butter, and sprinkle with granulated sugar.

Place another sheet of parchment paper on top of each pastry, then add another baking sheet on top to weigh down.

Bake for 15-20 minutes until golden brown, remove top sheets, and bake for 5 more minutes to crisp the surface.

Heat milk with vanilla bean in a saucepan until it just begins to simmer.

Whisk together egg yolks, sugar, cornstarch, and salt in a separate bowl until pale and smooth.

Slowly pour hot milk into egg mixture while whisking constantly to temper the eggs.

Return mixture to saucepan and cook over medium heat, whisking continuously, until thickened (3-5 minutes).

Remove from heat, whisk in butter until melted, transfer to bowl, cover with plastic wrap, and refrigerate for 2 hours.

Cut cooled puff pastry into equal rectangles using a sharp knife.

Whip chilled pastry cream with electric mixer for 1-2 minutes to lighten texture.

Place one pastry rectangle on serving plate and spread generous layer of pastry cream on top.

Sprinkle crushed pistachios and mini chocolate chips over cream layer.

Add another pastry rectangle and repeat layering with cream, pistachios, and chocolate chips.

Top with final pastry layer and dust generously with powdered sugar.

Garnish with crushed pistachios, chocolate chips, and fresh maraschino cherries. Serve immediately.