Let the chocolate melt in a bain-marie.
Put the cookies, butter, salt, and cocoa powder in a food processor and mix finely. Pour into a springform pan lined with plastic wrap, first press evenly against the sides and then press evenly and flat on the bottom, the goal is to have crust on the sides and bottom, this is easy with a straight glass with a flat bottom.
Whip the cold heavy cream until soft peaks form and place in the fridge.
Pour the egg whites and sugar into a mixing bowl and whip for 5 minutes until the sugar granules are completely dissolved and the egg whites are nicely whipped to stiff peaks.
Fold the whipped cream into the melted chocolate, then fold in the meringue in two batches to create a light, homogeneous mousse, pour into the mold and spread evenly. Refrigerate for at least 4 hours to set.
Place a frying pan on the heat, add the sugar and let it melt and then caramelize, stir in the sesame seeds and mix well, pour out onto baking paper, do not touch as it is super hot, place another baking paper on top and roll very thin. Let it harden and cool.
Whip the cream for the topping with sugar but not too stiff.
Release the cake from the mold, remove the plastic wrap, place on a plate and spoon the whipped cream on top, make swirls and spread a little open, break the sesame crunch into large pieces and stick them into the whipped cream. Cut the cake with a warm knife that you dip in hot water each time.
Tips
You store the sesame crunch in a cool place in a closed box. You can store the cake covered in the fridge for 4 days. You can freeze the cake for up to 3 months.