MAKE THE SPONGE CAKE. Beat the egg whites until stiff peaks form.

In a bowl, mix the egg yolks with the sugar. Add the cornstarch and flour. Gently fold in the beaten egg whites using a spatula.

Preheat the oven to 350°F (180°C). Spread the mixture onto a baking sheet lined with parchment paper and bake for 12 minutes. When done, place the sponge cake on a clean kitchen towel and moisten it with a sugar-water mixture.

MAKE THE PRALINE. Toast the hazelnuts in the oven at 410°F (210°C) for 10 minutes, watching carefully. The hazelnuts are ready when you see a dark spot in the center after cutting one in half.

Blend the hazelnuts and sugar together very finely until you get a paste.

MAKE THE PRALINE PASTRY CREAM. Heat the milk in a saucepan and bring to a boil.

In a bowl, crack the egg and mix with the sugar. Add the flour and cornstarch. Add a little of the hot milk and stir again until the mixture is less thick.

Pour the mixture into the saucepan with the remaining milk and cook for 3-4 minutes, stirring constantly. The cream is ready when it thickens.

Remove from heat and add 2-3 tablespoons of praline to taste. Add 1/2 cup (about 125 grams) of butter to the hot cream and mix. Let cool.

Soften the remaining butter (leave it out overnight). Once the cream has cooled, mix it in a stand mixer. The cream must be very cold to whip properly! Gradually add the butter and mix until the cream becomes fluffy.

Once the cream is ready, spread some over the sponge cake, then roll it up to form a log. Cover the log completely with the remaining cream.

For decoration, use your imagination! Here, I made small cream-filled choux pastries to evoke the Paris-Brest.