1. Puff pastry :
Place all the ingredients except the kneading butter (remember to spread it out in a rectangle of parchment paper to make it easier) in the bowl of your food processor fitted with the hook. Knead for 10 minutes at slow speed, then for 5 minutes at medium speed. The dough should be smooth and come away from the sides of the bowl. Form the dough into a disk, wrap it in plastic film and leave it to rest for 20 to 30 minutes at room temperature (depending on the temperature of your kitchen). Then punch down the gas, film it and place it in the fridge overnight. The next day, start by rolling out the dough to a thickness of just under 1 cm and incorporating your butter. Your dough should always be rectangular. Take it lengthways, roll it out and give it a simple turn by folding the dough over itself like a wallet. Place in the fridge for at least 30 minutes.
Take it lengthwise and give it a 2nd single turn. You’ll need to make 3 rounds in all, respecting the all-important chilling time each time. At the end of the 3 rounds, place in the fridge for at least 1 hour. (Alternatively, you can simply make 1 double and 1 single round. For the double round, fold the top and bottom of the dough towards the middle and seal with your fingers before folding into a wallet.)
Once the dough has cooled, roll it out into a 60 x 40 cm rectangle. Roll it out, starting with the long side furthest from you. Using a sharp knife or unscented dental floss, cut slices of dough weighing around 95 grams and place them on an oven tray in cookie cutters 10 cm wide and 3 cm high. Leave the New York rolls to rise for 2 hours at room temperature, then place a Silpat or sheet of baking parchment on top, cover with a baking tray and bake at 170°C for around 30 minutes, until golden-brown (if possible, avoid opening the oven door until baking is almost complete). Leave to cool completely.
2. Pastry cream with chocolate
In a bowl, whisk together the yolks and sugar, then add the cornstarch. Heat the milk, then pour it gently over the yolk mixture while whisking. Return to the saucepan and cook the crème pâtissière, bringing to the boil (while whisking constantly) and maintaining the boil for 1 minute before removing the saucepan from the heat and adding the chocolate topping. Pour the chocolate custard into a clean mould, cover with plastic wrap and leave to cool completely. Keep for 48 hours in the fridge.
3. Assembly:
Whip the chocolate custard until smooth. Hole the New York rolls in 3 different places using a wooden chopstick, then fill with the cream. Garnish with runny chocolate topping and sprinkle with hazelnut chips and whole hazelnuts.
Enjoy during the day.
