1-First Step: Prepare Puff Pastry Base Preheat your oven to 350°F (175°C). Line a baking tray with parchment paper. Lay out the puff pastry sheets on the tray and bake for 10-15 minutes until golden and crisp. Once baked, transfer onto wire racks to cool while you prepare the custard.

2-Second Step: Make the Custard Base In a medium saucepan, heat 3 cups (720 ml) of whole milk until boiling. While waiting, whisk egg yolks and granulated sugar in a large bowl until fluffy. Gradually add flour, vanilla extract, rum (if using), and the remaining 1 cup (240 ml) milk to the yolk mixture, mixing well to combine.

3-Third Step: Combine Milk and Egg Mixture Slowly pour hot milk into the egg yolk mixture, whisking constantly to temper the eggs. Return the mixture to low heat and cook, stirring frequently, until it thickens into a smooth custard consistency. Remove from heat and allow to cool slightly.

4-Fourth Step: Incorporate Egg Whites Beat the egg whites until stiff peaks form. Gently fold these into the warm custard to lighten the texture, giving you a creamy yet airy vanilla custard.

5-Fifth Step: Assemble Bottom Layer and Chill Place one baked puff pastry sheet at the base of a large baking dish (around 20 x 30 cm). Pour the prepared custard evenly over the pastry, smoothing the top. Cover and refrigerate for 1-2 hours until the custard sets firmly.

6-Sixth Step: Whip Cream and Apply Topping Whip chilled heavy cream with powdered sugar to soft peaks. Spread the whipped cream evenly over the set custard layer, creating a light, fluffy top.

7-Seventh Step: Add Top Pastry Layer Cut the second puff pastry sheet into neat squares and arrange them carefully on top of the whipped cream layer. This adds a crispy texture that contrasts with the creamy layers beneath.

8-Final Step: Chill and Serve Refrigerate the assembled dessert for an additional 2 hours to allow flavors to meld and texture to firm. Before serving, dust generously with powdered sugar for an elegant finish. Cut into squares and enjoy a classic, crowd-pleasing treat.