Unroll the puff pastry and cut 27 small circles from the rolls with a 6 cm pastry cutter.
With a slightly smaller pastry cutter, cut a hole in the center of 18 of the 27 circles of pastry, in order to obtain rings.
Place the unperforated circles on the baking tray lined with parchment paper, brush with milk, then place 2 rings on each circle, overlapping each other, trying to match the edges, also brushing the two rings with milk before overlapping them, so that they adhere well.
Bake for about 10 minutes in a preheated convection oven at 200 ° C, then take out of the oven and leave to cool.
When the vol au vents are completely cold and just before serving, fill with the Nutella cream.