Preheat the Oven and Prepare the Pastry:

Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Unfold the thawed puff pastry sheet onto a lightly floured surface and gently roll it out into a slightly larger square, about 1/8 inch thick.

Using a sharp knife or pizza cutter, cut the pastry into even squares. Choose a size you like, keeping in mind that larger squares will require more custard and whipped cream per layer.

Bake the Pastry Squares:

Carefully place the pastry squares on the prepared baking sheet, leaving some space between them to allow for puffing.

Lightly prick the center of each square a few times with a fork to prevent excessive puffing in the middle.

Bake for 20-25 minutes or until the squares are golden brown and puffed. Remove from the oven and cool completely on a wire rack.

Make the Vanilla Custard:

In a medium saucepan, whisk together the milk, sugar, and cornstarch until smooth.

Heat the mixture over medium heat, whisking constantly, until it thickens and starts to bubble.

In a small bowl, whisk the egg yolks. Slowly whisk the hot milk mixture into the yolks to temper them, whisking constantly to prevent curdling.

Return the combined mixture to the saucepan and cook over medium heat, whisking continuously for 1-2 minutes until the custard thickens enough to coat the back of a spoon.

Remove from heat, stir in the vanilla extract, then pour into a bowl. Cover the surface with plastic wrap to prevent a skin from forming. Let it cool to room temperature, then refrigerate for at least 1 hour.

Whip the Cream:

In a chilled bowl, use an electric mixer to whip the heavy cream until stiff peaks form. Take care not to over-whip, as the cream can become clumpy.

Assemble the Squares:

Once the custard is chilled and the pastry squares are cooled, start assembling.

Place a pastry square on a plate and spread a generous layer of custard on top, leaving a small border around the edges.

Add a heaping spoonful of whipped cream over the custard.

Top with another pastry square to create a sandwich. Repeat with the remaining squares, custard, and whipped cream.

Finishing Touches (Optional):

Dust the top of the assembled squares with powdered sugar for added sweetness and elegance.

Feel free to get creative—drizzle melted chocolate, garnish with fresh berries, or sprinkle chopped nuts on top.