Start by rolling out your puff pastry on a lightly floured surface until it's about a quarter-inch thick. Cut into rectangles for your baking tray.

Chill the puff pastry in the refrigerator for about 15 minutes while preheating the oven to 400°F (200°C).

Bake the chilled puff pastry rectangles on a lined baking sheet for 20-25 minutes until golden brown.

In a medium saucepan, whisk together eggs and sugar until combined. Heat milk until just boiling, then whisk into egg mixture.

Cook the custard over medium heat, stirring continuously until it thickens, about 8-10 minutes. Stir in vanilla and salt.

Layer a piece of baked puff pastry in a serving dish, spread custard, and repeat layers until finished.

Cover and chill the assembled cake in the refrigerator for at least 1 hour.

Slice the chilled cake and serve, optionally dusting with powdered sugar or adding fresh fruits.