Put the eggs, sugar, vanilla sugar and cornstarch in a saucepan and whisk together well until smooth.

Pour in the hot milk and cook over low heat, stirring constantly, until it thickens and comes to a boil.

Immediately transfer the finished cream to another bowl, add chopped chocolate and mix well with a whisk until smooth, then fold in the cocoa powder. Cool the cream, stirring constantly.

In a saucepan, melt the butter with the honey, add the baking soda and cook for a couple of minutes until the mixture increases in volume and turns caramel-colored, then remove from heat.

In the mixer bowl, beat the eggs with salt and sugar for a couple of minutes, pour in the butter-honey mixture and beat again.

Sift in the flour with vanillin and cocoa powder in portions and mix - you'll get a thin, liquid batter.

Divide the batter into about 2 parts (340 g each) and spread thinly with a spoon or spatula on parchment on a 40x30 cm baking sheet. Bake the layers one at a time, 10 minutes each at 180 C.

Split each cooled layer into 2 pieces and trim them, keeping the trimmings for the crumb coating.

Spread cream between the layers, including on top, about 4 tbsp per layer, and coat the top and sides with the crumb. Refrigerate the cake overnight. Enjoy!