In a saucepan, bring the water, butter, and salt to a boil, stirring regularly with a spatula. Make sure it comes to a strong boil, but don’t let it boil for too long or the liquid will evaporate.

Remove from heat, add the sifted flour all at once (to avoid lumps), and mix gently. Return to the heat and cook the dough until it forms a ball that pulls away from the sides of the pan (this happens quickly).

Transfer the dough to a mixing bowl and spread it along the sides to help it cool (this is called 'decuver').

In a separate bowl, crack 4 eggs (about 200 g) and beat them with a fork. Add one third of the eggs to the dough and mix until fully incorporated. Repeat with the remaining two thirds, adding in portions.

Check the consistency of the dough using the 'peak test' (see reference for explanation). If the dough is too dry, add part of the fifth egg and check again. Continue until you reach the perfect consistency.

To shape the large Paris-Brest: Place the dough in a piping bag fitted with a plain 14 mm tip. Pipe the Paris-Brest onto a baking sheet lined with parchment paper (greased if needed; do not use a silicone mat). Draw a 20 cm (8-inch) circle, pipe one ring along the outside of the circle, then a second ring just inside the first. Pipe a third ring on top, overlapping the two rings.

Brush the Paris-Brest with a little beaten egg mixed with a splash of milk. Run the flat side of a fork dipped in water over the top to create ridges. Sprinkle with sliced almonds.

Bake in a preheated oven at 350°F (180°C) for 40 to 45 minutes for a large Paris-Brest, or 30 minutes for small ones. After 25 to 30 minutes of baking, open the oven door briefly (do not open earlier or the pastry may collapse).

Let cool on a wire rack, then slice the choux rings in half with a serrated knife.

For the Praline Mousseline Cream

Pour the milk into a saucepan (reserve 3 to 4 tablespoons) and bring to a boil.

Meanwhile, whisk the egg yolks with the sugar and the reserved milk until pale, then add the cornstarch and mix until just combined.

Remove the milk from the heat and slowly pour it over the egg mixture, whisking gently.

Pour the mixture back into the saucepan and cook for 1 to 2 minutes, stirring constantly, until thickened. Stop cooking as soon as it comes back to a boil.

Remove from heat, add 1/2 cup (110 g) of butter to the cream, strain it, and transfer to a bowl. Cover with plastic wrap directly on the surface and let cool completely.

In a stand mixer bowl, cream the remaining butter, then add the praline paste and beat until light and fluffy.

Once well mixed, add the cooled pastry cream in three additions, beating well after each. Transfer the praline mousseline cream to a piping bag fitted with a star tip (E8).

Pipe the praline mousseline cream onto the bottom half of each Paris-Brest, cover with the top half, and dust with powdered sugar.