Melt the unsalted butter, granulated sugar, and honey together over low heat until smooth.

Remove the pan from the heat and stir in the baking soda until the mixture foams.

Let the honey mixture cool for 10 minutes until warm rather than hot.

Beat in the eggs one at a time, mixing fully after each egg.

Add the all-purpose flour and knead until a smooth dough forms.

Chill the dough until firm enough to roll, then knead it briefly again.

Divide the dough into 6 equal portions and keep the portions covered.

Roll one dough portion thinly on parchment paper into a round layer.

Trim the layer with the cake ring or a knife, reserving every dough trimming.

Bake the layer at 180°C for about 10 minutes, until lightly golden.

Repeat the rolling and baking process with the remaining 5 dough portions.

Bake the reserved dough trimmings into an additional cake layer until lightly golden.

Cool all cake layers completely, then crumble the extra layer into fine crumbs.

Beat the mileram sour cream and powdered sugar until smooth.

Fold the whipped cream into the sour-cream mixture until the filling is uniform.

Place one cake layer on the cake stand and spread it with an even layer of filling.

Stack the remaining cake layers with filling between each layer.

Cover the top and sides of the cake with the remaining filling, then coat it with cake crumbs.

Chill the assembled cake for at least 8 hours so the layers soften before serving.