Roll out the puff pastry and cut out as many hearts as you like using a 4-5 cm heart shape (re-knead the remaining pie dough, roll it out with a rolling pin, and cut out more hearts).
Using a small heart-shaped cutter, cut the salami, smoked salmon, and cheese hearts and place them in the center of the pastry heart. Alternatively, place the pesto on top of the pastry, leaving the edges intact.
Fill only half of the hearts.
Using the same small cutter, cut out the hearts from the remaining puff pastry. Remove the center pieces (you can also remix these and continue making other vol-au-vins) and use the edges to complete your vol-au-vin creation. Wet the free end of the stuffed heart and place the newly created heart with the hole on top of it.
Place the heart-shaped vol-au-vin on a baking sheet lined with baking paper, spacing them slightly apart, and bake in a preheated ventilated oven for about 15-20 minutes, or until golden brown at 200°C.
Now that the puff pastry hearts are ready, all you have to do is serve them.