Prepare 2 baking sheets by covering them with parchment paper, then with a pencil, draw 8 circles of 4 ” (10 cm) in diameter on the parchment paper. Set aside.

In a thick-bottomed saucepan, boil the water, milk, butter, salt, and sugar.
When the mixture reaches a boil, pour in the flour all at once and stir vigorously with a wooden spoon for 1 minute until a ball of dough forms that detaches completely from the bottom of the saucepan.
Pour this ball into a bowl, then add the eggs one by one, beating quickly
The puff pastry should have a smooth consistency, but it should not be too soft.
Preheat the oven to 425 F (220 C).
Put the pastry in a pastry bag without a tip, then deposit the puff pastry following the circles you drew. The width of the pastry circle should be 2 cm. If it’s not the case, make a second ring of pastry.

Bake for 15 minutes, then reduce the oven to 375 F (190 C) and continue baking for 20 minutes.
Remove the Paris-Brest from the oven and let cool on a rack.

Praline mousseline cream:
Heat the milk with 2 tablespoons of sugar taken from the initial amount of sugar.
Whiten the remaining sugar with the egg yolks.
Add the cornstarch and beat until a smooth cream is obtained.
Gradually pour the boiling milk over this mixture and pour the preparation into the saucepan.
Bring to a boil, stirring well, until the mixture thickens.
Add the praline and mix until it is well melted and the cream is smooth.
Add half of the butter and mix well.

Cover the saucepan with plastic wrap and let cool completely.

Put 1/3 of the butter in the mixer bowl and beat at high speed to cream, incorporating 1/3 of the praline cream.
Repeat the operation 2 times.
Refrigerate before filling a pastry bag, then filling the Paris-Brest, cut in half in the thickness.
Dust with powdered sugar and enjoy.