Croissants with lemon meringue filling

Ingredients:

• 1 sheet frozen buttered puff pastry, thawed
• 1 large egg (separate the yolk from the white) + 1 egg white
• 1/3 cup sugar
• 1 teaspoon freshly squeezed lemon juice
• A pinch of salt
• 3/4 cup lemon curd
• Flour, for work

Preparation:

1. On a lightly floured surface, roll out the puff pastry into a 30x40cm rectangle. Cut it in half crosswise to make two 20x30cm rectangles, then cut each piece crosswise into thirds to make six 10x20cm rectangles. Cut each rectangle in half diagonally to make 12 triangles.
2. Line a baking sheet with parchment paper. Loosely roll each triangle of dough, starting from the shortest edge, into a log; place them seam-side down on the prepared baking sheet, about 4 cm apart. Refrigerate until the dough has set, about 30 minutes.
3. Preheat oven to 175°C (350°F). Whisk the egg yolk with 1 teaspoon of water; brush the dough with the mixture. Bake until golden brown, 30-35 minutes. Reduce oven temperature to 150°C (300°F) and continue baking until the croissants are set, another 35-40 minutes. Let cool completely.
4. Prepare the meringue.
   
   In a large heatproof bowl, whisk the egg whites, sugar, lemon juice, and salt until smooth. Place the bowl over a saucepan filled with 2.5 cm of simmering water (the bottom of the bowl should not touch the water). Heat, whisking, until the mixture is warm and the sugar is completely dissolved, 2-3 minutes. Remove the bowl from the water bath and beat the whites with an electric mixer at medium speed until the meringue cools and forms stiff, glossy peaks, 5-10 minutes.
5. Poke a hole in the bottom of each croissant with a thick skewer or chopstick, wiggling it around to create a small cavity. Fill a zip-lock plastic bag with lemon curd; snip off the corner. Squeeze about 1 tablespoon of lemon curd into each croissant. Spoon the meringue over the top of each croissant, swirling it with the back of a spoon. Lightly toast the meringue with a kitchen torch.