1) Preheat oven to 400F.
2) Prepare 2 baking sheets with parchment paper and set aside.
3) Cut pastry dough into 3 strips along fold marks. Place on a baking tray and make a couple of holes in each dough with a fork. Bake for 15 minutes or until golden brown. Let cool on a rack.
4) In a medium saucepan place the milk and bring to a simmer. Meanwhile, in a small bowl whisk together the sugar, cornstarch, and salt
5) Gradually add the cornstarch mixture to the milk and cook, stirring frequently, for about 6 minutes or until thickened. Beat the yolks and cook for a further 2 minutes, stirring frequently.
6) Add the vanilla extract and butter, and remove from heat.
7) Let cool to room temperature, cover and refrigerate until ready to use. Using a fork, divide each dough into 2 layers. Spread pastry cream on 1 cake layer.
Repeat the layers. Finish with a layer of arequipe or dulce de leche.
