01 -
Set oven to 200°C. Line a baking sheet with parchment paper.
02 -
Cut thawed puff pastry into rounds with a cutter. Arrange on the baking sheet and prick lightly with a fork. Bake for 15–18 minutes until golden and crisp. Transfer to a rack and cool fully.
03 -
In a saucepan, whisk together whole milk, granulated sugar, cornstarch, and salt. Heat over medium, stirring continuously, until thickened and smooth.
04 -
In a separate bowl, whisk egg yolks. Gradually add a small amount of the hot milk mixture to the yolks, whisking constantly. Return this tempered egg mixture to the saucepan.
05 -
Continue cooking, stirring until the custard is silky and thick, about 5 minutes. Remove from heat. Blend in vanilla extract and unsalted butter until glossy. Pour into a bowl, press plastic wrap directly onto the surface, and refrigerate for 30 minutes to set.
06 -
Slice cooled pastry rounds horizontally. Pipe or spoon the chilled custard evenly onto the bottom halves. Cover with the top halves to form sandwiches. Finish with a dusting of powdered sugar.