Beat the eggs and sugar with a mixer to whitening. Slowly, spoon by spoon, add the breadcrumbs and flour (alternating 1 spoon of breadcrumbs, 1 spoon of flour) as if for a cake dough, but if it starts getting too thick, stop adding one of the 2.
Add the finely ground walnuts. Smear a 10 diameter cake form with removable sides with butter. Bake the layers for 30-40 minutes at 338°F (170 °C). Most of the time toward the end is spent drying them.
Once cooled, cut them in two and moisten well with rum / brandy. Fill with cream that you've prepared (the usual way) from the products listed, without adding the butter.
Once the cream has cooled completely, mix it thoroughly with the butter that you've beaten to a soft foam ahead of time. Coat the walnut cake with the remaining cream and add chocolate chips if you like.
Keep for a few hours in the refrigerator before serving.