Preheat the oven to 400°F (200°C).

Roll out the puff pastry on a floured surface to about 1/8-inch thickness.

Cut the pastry into rectangles, about 3x5 inches.

Place the rectangles on a baking sheet lined with parchment paper and bake for 20-25 minutes until golden brown and puffed.

In a saucepan, whisk together milk, sugar, and flour over medium heat until thickened.

Temper the egg yolks by whisking them in a bowl, then gradually add the hot mixture to the yolks, stirring constantly.

Return the mixture to the saucepan, cook until thickened, then add butter and vanilla extract.

Once the pastry is cooled, layer them with the cream filling in between and dust with confectioners' sugar on top.