Lay out the puff pastry and cut it into rectangles. Arrange them in an oven dish with baking paper and bake in a preheated oven until ready. Let them cool.
Beat the cream until thickened with a mixer. Pour the milk into a bowl and add the pudding. Beat with a mixer to a fluffy consistency. Combine the 2 creams and stir until homogeneous.
In a plate, crumble 2-3 puff pastry rectangles into crumbs.
Cut the puff pastry rectangles down the middle and fill them with cream. Dip the tops of the Napoleon desserts in cream, then in the crumbs. Arrange in a platter and leave them for 2-3 hours to take in the cream and soften.
They're spectacular! Bon appetit!