On a lightly floured piece of parchment paper, roll half of Buttery Puff Pastry into a 16x12-inch rectangle. Place on a large jelly-roll pan. Brush with 2 tablespoons (30 grams) cream, and sprinkle with 1 tablespoon (12 grams) granulated sugar. Top with parchment paper, and place another large jelly-roll pan on top of pastry.
Bake until golden brown, 20 to 22 minutes, pressing down on middle of top pan halfway through baking to release air from pastry. Remove from oven, and press down on pan again. Remove top pan and parchment paper; let cool completely on pan. Repeat with remaining Buttery Puff Pastry, 2 tablespoons (30 grams) cream, and 1 tablespoon (12 grams) granulated sugar.
In a large saucepan, whisk together cornstarch and remaining 1½ cups (300 grams) granulated sugar. Add milk and remaining 3½ cups (840 grams) cream, whisking until smooth. Bring to a low boil over medium heat.
In a medium bowl, whisk together egg yolks and zest. Gradually add 2 cups hot milk mixture to egg mixture, whisking constantly. Whisk egg mixture into remaining hot milk mixture in saucepan. Cook over medium heat, whisking constantly, until thickened. Remove from heat; whisk in butter, orange liqueur, and salt. Let stand at room temperature for 10 minutes. Transfer to bowl, and press a piece of plastic wrap directly onto surface of custard to prevent a skin from forming.
Line a 9x13-inch baking pan with parchment paper, letting excess extend over sides of pan. Using a pastry cutter, cut pastry sheets into 9x13-inch rectangles. Place one pastry sheet in prepared pan. Pour custard over top, and cover with remaining pastry sheet, pressing down gently. Refrigerate until set, 3 to 4 hours.
To serve, dust with confectioners’ sugar. Using excess parchment as handles, remove from pan. Using a serrated knife, gently cut into squares.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/orange-custard-bars/