Remove the puff pastry from the fridge, unroll it and leave to stand for at least 20 minutes.
Cut the puff pastry into 20 square pieces, fold each piece diagonally and cut it along the sides approximately 0.5 cm from the edge, leaving the tip attached.
Open up each square again and fold the cut-out strips using the attached tips to help you, overlapping them in order to create an edge. Cut the Rossini cheese into thin slices and arrange on top of the pastry. Place the tartlets onto an oven tray covered with baking paper and bake in a pre-heated oven at 170°C for approximately 10 minutes.
Remove from the oven and leave to cool. Garnish with a teaspoon of semi-whipped cream, place a hazelnut on top and serve immediately.