Instructions
1. Prepare the Puff Pastry
Preheat your oven to 400°F (200°C). Line two baking sheets with parchment paper. Roll out each puff pastry sheet slightly to a 9×9-inch size and prick all over with a fork to prevent excessive puffing. Place the sheets on the trays and cover each with another sheet of parchment and a second tray to weigh it down.
2. Bake to Golden Perfection
Bake for 35–45 minutes until golden brown and crisp, checking around the 30-minute mark. Once done, allow the pastry to cool completely.
3. Trim the Edges
Using a serrated knife, carefully trim the puff pastry sheets to fit an 8×8-inch square pan. Place one sheet on top of the other while trimming to keep edges aligned.
4. Make the Custard
In a medium saucepan, whisk together sugar, cornstarch, and salt. Add egg yolks and mix thoroughly. Meanwhile, warm the milk in a separate saucepan over medium heat until steaming (do not boil).
Slowly temper the eggs by pouring in about 1 cup of warm milk, whisking constantly. Then, gradually add the tempered egg mixture back into the remaining milk in the saucepan. Cook over medium heat, whisking constantly, until the custard thickens and begins to bubble, about 5–7 minutes. Remove from heat, then stir in the vanilla seeds and cubed butter until smooth.
5. Assemble the Vanilla Slice
Line an 8×8-inch pan with aluminum foil, leaving an overhang for easy removal. Place one puff pastry sheet on the bottom. Pour the warm custard over the pastry and smooth with a spatula. Top with the second pastry sheet, pressing gently to adhere. Cover and chill for at least 4 hours or overnight.
6. Slice and Serve
Lift the chilled slice from the pan using the foil overhang. Place on a cutting board and slice into 9 large or 16 smaller squares. Dust with powdered sugar and serve.
Tips & Storage
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Make-Ahead: This slice can be prepared up to 24 hours in advance; the flavors improve as it rests.
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Storage: Keep leftovers in an airtight container in the fridge for up to 3 days.
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Freezing: Wrap tightly and freeze for up to 1 month. Note that custard texture may change and puff pastry may lose crispness. Thaw overnight in the refrigerator.
Enjoy this luscious vanilla slice that pairs perfectly with a cup of tea or coffee for an indulgent treat anytime!