Vanilla Custard Cream Squares

These rich, creamy vanilla custard squares—often known as vanilla slices, mille-feuille, or slices a la vanilla—feature layers of crisp, buttery puff pastry sandwiching a thick, velvety vanilla pastry cream, finished with a smooth glaze.

Ingredients

• 2 sheets of frozen puff pastry, thawed according to package instructions
• 1 tablespoon granulated sugar (for dusting)

• 2 cups whole milk
• 1 teaspoon pure vanilla bean paste (or 1 split vanilla bean)
• 4 large egg yolks
• 1/2 cup granulated sugar
• 1/3 cup cornstarch
• 2 tablespoons unsalted butter (softened)
• A pinch of salt

• 1 1/2 cups powdered sugar
• 2 to 3 tablespoons heavy cream or whole milk
• 1 teaspoon vanilla extract
• 1 oz semi-sweet chocolate (optional, for traditional feathered decoration)

Instructions

1. Bake the Puff Pastry

1. Preheat your oven to 400°F (200°C) and line two baking sheets with parchment paper.
2. Unroll the thawed puff pastry sheets onto the baking sheets. Prick the surface thoroughly all over with a fork to prevent massive, uneven puffing.
3. Cover each sheet with another piece of parchment paper and place a second baking sheet directly on top to keep the pastry flat and crisp.
4. Bake for 15 to 18 minutes until golden brown. Remove the top baking sheet and parchment, dust the top lightly with a tablespoon of sugar, and return to the oven for 2 to 3 minutes until caramelized and crisp. Let cool completely, then trim the edges so both sheets are the exact same size.

2. Make the Vanilla Pastry Cream

1. In a medium saucepan, gently heat the whole milk and vanilla bean paste over medium heat until it is just simmering (do not boil).
2. In a separate bowl, whisk together the egg yolks and granulated sugar until pale and slightly thickened. Whisk in the cornstarch and salt until smooth.
3. While whisking constantly, slowly pour about half of the hot milk into the egg mixture to temper the eggs (this keeps them from curdling).
4. Pour everything back into the saucepan over medium-low heat. Whisk continuously and vigorously until the mixture thickens into a glossy, pudding-like consistency (about 3 to 5 minutes).
5. Remove from heat and stir in the softened butter until completely smooth.
6. Press plastic wrap directly onto the surface of the cream to prevent a skin from forming, and let it chill in the refrigerator for at least 2 hours until fully set.

3. Assemble the Squares

1. Line an 8×8-inch baking pan with parchment paper, leaving overhangs on the sides so you can easily lift the squares out later.
2. Place your first baked puff pastry sheet at the bottom of the pan.
3. Whisk the chilled pastry cream briefly to loosen it up, then spread it evenly over the pastry layer.
4. Gently press the second puff pastry sheet down on top of the cream.

4. Glaze and Chill

1. Whisk the powdered sugar, heavy cream, and vanilla extract together until smooth and thick. Spread it evenly over the top pastry layer.
2. (Optional traditional touch): Melt the semi-sweet chocolate, put it in a small piping bag with a tiny tip, pipe parallel lines across the white glaze, and run a toothpick back and forth through the lines to create a feathered chevron pattern.
3. Refrigerate the assembled squares for at least 4 hours (or overnight) so the custard sets firmly and the pastry softens just enough to cut cleanly.
4. Use the parchment paper to lift the slab out, slice into neat squares with a sharp, serrated knife, and serve chilled.