Mix the onions with the cream cheese, bacon, chives and parsley. Mix the egg yolks and milk.
Fill the puff pastry sheets in the middle with about 1.5 teaspoons of the cream cheese mixture, press the edges together well and brush with the egg yolk mixture. Place on a baking sheet lined with baking paper.
Bake in the preheated oven at 200 ° C for about 20 minutes.
Possible variation: Fill with Nutella or with a mixture of tomato and mozzarella.