Put the eggs, butter, honey, sugar, orange zest and salt in a heat-resistant mixing bowl and heat the mixture in a bain-marie, stirring constantly until the butter has melted.
Add baking soda, stir thoroughly, and continue to heat (not boil) the mixture in the water bath, stirring occasionally, until it has about doubled in volume, about 15 minutes.
Take the honey mixture from the water bath and add flour in batches, mixing first with a spoon while the mixture is still hot, then knead with your hands to form a soft dough.
Divide the dough into 7 equal pieces and cover them to prevent them from drying out. First roll out one piece of dough very thinly on a sheet of baking paper, cut out a Ø 24 cm circle from it, pierce it several times with a fork and bake it in a preheated oven at 180 °C top and bottom heat for about 4 minutes until golden brown. Repeat the same with the remaining pieces of dough. Let all the cake layers cool down.
Roll out the leftover dough thinly, bake it in the same way as the cake layers, let it cool and crumble it finely.