INVERSE PUFF PASTRY
In the bowl of a mixer fitted with a flat beater, mix the flour (1) and dry butter cubes. Once the mixture is homogeneous, remove to a baking sheet and cover with film. Leave in the refrigerator overnight. In the bowl of a mixer fitted with a flat beater, rub the cubed dry butter and salt through the flour (2) to a crumble. Next, add the water and white vinegar. Once the mixture is homogeneous, spread onto a baking sheet and leave in the refrigerator overnight. The next day, give the dough three double turns, resting for 3 h between each turn. Leave the dough piece to rest overnight. Roll out the dough to a thickness of 2 mm, then rest the dough. Leave to rest for an h in the refrigerator, then cut out 14 cm x 3.5 cm rectangles. Place onto tray with a baking sheet and rack set 1.5 cm above. Bake in a fan-assisted oven at 170 °C for 40 min.

DECORATION
Make a caramel with the sugar, then pour onto a sheet and allow to cool before processing into a powder. Sprinkle brown sugar over the puff pastry rectangle and use a small sieve to dust with a fine layer of caramel powder. Place in an oven at 170 °C for 1 min to melt the caramel. Chill.

VANILLA CRÈME PÂTISSIÈRE
Heat the milk. Whisk the caster sugar, egg yolks, whole eggs and Caviani in a bowl, then add the corn starch. Pour in the hot milk and return to the heat in a saucepan. Boil for 3 min, take off the heat, and add the cubed butter. Cool quickly before using.

VANILLA DIPLOMAT CREAM
Smooth the Caviani crème pâtissière. Melt the hydrated gelatine and mix together with some of the crème pâtissière, then mix with the remaining crème pâtissière. Whip the cream until it has a firm texture, then mix all the ingredients together. Transfer to a piping bag fitted with a No. 22 tip. Immediately pipe onto a rectangle of puff pastry, then arrange the second puff pastry rectangle on top.