Preheat your oven to 400°F (200°C). Roll out the puff pastry until it’s about 1/8-inch thick, line a 9x13-inch baking dish with it, and bake for 15 minutes until golden brown. Let cool.

Combine 4 cups of whole milk and 1 1/2 cups of sugar in a saucepan over medium heat until warm. In a bowl, whisk together 1/4 cup of cornstarch and 8 eggs, then gradually whisk in the milk mixture.

Return the custard mixture to the saucepan and cook over medium heat while stirring constantly for 10-15 minutes until thickened. Remove from heat and stir in 3 teaspoons of vanilla extract.

Pass the custard through a fine-mesh strainer into a clean bowl. Allow to cool slightly before pouring into the cooled puff pastry.

Pour the custard evenly over the pastry and cover with plastic wrap. Refrigerate for at least 4 hours to set.

Whip 2 cups of heavy cream until soft peaks form. Spread evenly over the chilled custard layer.

Before serving, dust the whipped cream layer with powdered sugar and cut into squares.