Steps

• Sift the flour onto a piece of parchment paper.

  Take a piece of parchment paper and, using a plate or the ring of a cake pan, draw a circle with a diameter of 8 inches with a pencil. Then place the parchment paper upside down on the baking tray, so that the pencil does not come into contact with the choux pastry.
  
  Put the water, butter, and salt in a saucepan and heat over medium heat, stirring, until the butter has melted and the water starts to boil.
  Remove the pan from the heat, pour in the flour at once, and mix quickly with a wooden spoon, so that no lumps form and until you obtain a compact dough.
  Put the pan back on the heat and cook over medium-low heat, continuing to stir the choux pastry with the help of a spoon for a couple of minutes, until it leaves a white film on the bottom of the pan.
  Transfer the mixture to the bowl of the stand mixer and turn it on for a minute to cool the dough a bit.

  Preheat the oven to 375 degrees Fahrenheit (static).

  Break the eggs into a small bowl and beat them a little with a fork.

  When the dough is warm but no longer hot, start adding the beaten eggs, a little at a time, until they are used up, continuing to work the dough with the paddle attachment of the stand mixer, until it has completely absorbed the eggs and is homogeneous and shiny.
  Transfer the choux pastry into a pastry bag with a star nozzle and make a circle on the parchment paper along the outer edge of the previously drawn circle. Then make another circle inside the one just made, so that it touches the first one. Then make two more circles on top of the ones just made, and finally a fifth one in the center, between the two layers just created. A total of 5 circles, two in the first two layers and the last one on top, to be precise.
  Brush the entire surface with the beaten egg and sprinkle with sliced almonds.
  Bake at 375 degrees for 35 minutes, without ever opening the oven!

  After the 35 minutes of baking, remove from the oven and very quickly, with a toothpick, pierce the choux pastry ring along the outer side and immediately put it back in the oven for another 15 minutes, placing a wooden spoon in the oven door to let the steam out. Turn off the oven and let the choux pastry ring rest inside for 15 minutes, keeping the door slightly open.

  Then take it out of the oven and let it cool completely on a rack.

  

• To prepare the coffee cream, put the milk, sugar, instant coffee, seeds of half a vanilla bean, and cornstarch in a saucepan. Put it on the stove and bring it to a boil, stirring. Let it boil, stirring, for about a couple of minutes, until the cream thickens.

  Remove from the heat, cover with plastic wrap in contact with the surface, so that a skin doesn’t form, and let it cool, or at least warm up.

  When the cream is warm, beat the butter in a bowl until it’s creamy. Add the coffee cream a spoonful at a time, continuing to beat, until you get a homogeneous cream. Cover with plastic wrap and place in the fridge for a couple of hours.

  

• When both the choux pastry ring and the cream have cooled down, you can proceed to assemble your Paris-Brest.

  Whip the cream and place it in the fridge.

  Put the hazelnut spread in a small bowl and heat it slightly in the microwave or in a bain-marie, just enough to make it a bit softer.

  Cut the hazelnuts in half.

  With a sharp knife, cut both along the outside and inside of the top ring of your choux pastry and remove it. Set it aside.

  Transfer the coffee cream into a piping bag and fill the bottom part of your choux pastry ring with it.

  Also transfer the hazelnut spread into a piping bag with a small round nozzle. Insert the nozzle into the coffee cream, inserting a bit of hazelnut cream into it. Proceed like this along the entire circle, inserting a bit of hazelnut cream every 3/4 inch approx., so that each slice will have a bit of hazelnut cream inside. With the remaining hazelnut cream, make a circle on the coffee cream.

  Sprinkle with some halved toasted hazelnuts.

  Transfer the whipped cream into a piping bag with a star nozzle and distribute it over the coffee cream. Garnish with the remaining toasted hazelnuts and place the top ring on the whipped cream to complete your Paris-Brest.

  Place in the fridge for about an hour before serving.