Heat the sugar and almonds in a large pan over low heat until the sugar caramelises. Do not stir. When the sugar is nicely golden-brown, pour on a sheet of aluminium foil to get a thin film. Leave to cool.
Crumble the croquant in a blender.

Preheat the oven to 180 °C. Line two equal cake tins with sheets of parchment paper.

To make the first pastry, beat the butter, egg yolks and sugar. Add the melted chocolate, almonds and breadcrumbs. Carefully stir in the whipped egg whites. Pour the mixture into the cake tins and bake for 25 minutes. Leave to cool.
Lower the temperature to 160 °C.

To make the second pastry, beat the egg whites until firm peaks form. Stir in the sugar gradually. Stir in the almonds and breadcrumbs gently, using a spatula. Bake in a cake tin lined with a sheet of parchment paper for about 40-50 minutes. Leave to cool.
Meanwhile, make the crème.

Beat the egg yolks, sugar and coffee. Place over steaming hot water and cook, stirring constantly, until the crème thickens. Leave to cool. Beat the butter and add to the cold crème. Stir in half the amount of the crumbled croquant using a spatula.
Place the dark pastry on a cake plate. Spread 1/3 of the crème on top. Top with the light-coloured pastry and spread with another 1/3 of the crème. Top with the other dark pastry. Spread the remaining crème over the top and sides of the cake. Decorate with the remaining croquant.
Refrigerate for 2 hours prior to serving.