Starbucks CopyCat Vanilla Bean Custard Danish

In a saucepan, whisk together the sugar, corn starch and salt.
Whisk in the egg yolks until smooth, then gradually whisk in the milk and cream.
Use a paring knife to split the vanilla bean lengthwise, and scrape out the seeds. Whisk the vanilla bean seeds into the custard.
Cook the custard over medium heat, whisking constantly, until the custard begins to thicken and bubble - this should take about 8-10 minutes. Once it begins to bubble, continue to cook for 1 full minute while whisking.
Remove from the heat and whisk in the butter.
Set aside and allow to cool to room temperature.

Preheat oven to 400F.
On a flat surface spread the puff pastry and gently roll out. Cut it into 6-8 equally sized squares or rectangles depending on the shape of your puff pastry. Place on the baking sheet.
Fill a piping bag with the custard and cut the tip off about 1 inch in. Pipe a line in the center of each puff pastry rectangle making sure to leave about half an inch on each side.
In a small bowl, whisk the egg and 1 tbsp water to make the egg wash. Dip a pastry brush in the egg wash, and brush the edges of the puff pastry.
Bake in the preheated oven for 15-16 minutes before pulling them out and letting them cool down on a cooling rack