1 sheet of frozen puff pastry, thawed
1 1/2 cups milk
1/2 cup sugar
pinch of salt
1 teaspoon vanilla extract
3 tablespoons cornstarch
3 egg yolks, beaten
1 tablespoon butter
1 cup arequipe or dulce de leche
Preheat oven to 400F.
Line 2 baking sheets with baking paper and set aside.
Cut the dough into 3 strips along the folds. Place on a baking sheet and poke a few holes in each dough with a fork. Bake for 15 minutes or until golden. Leave to cool on a wire rack.
Place the milk in a medium saucepan and bring to a boil. Meanwhile, whisk together the sugar, cornstarch, and salt in a small bowl.
Gradually add the cornstarch mixture to the milk and cook, stirring frequently, for about 6 minutes or until thickened. Beat the egg yolks and cook for another 2 minutes, stirring frequently.
Add vanilla extract and butter and remove from heat.
Allow to cool to room temperature, cover and refrigerate until ready to use.