Potato Pastry in the Shape of an Egg

Whisk together the flour, cocoa powder, baking soda, and baking powder, then sift the mixture.

Whip the eggs with the salt, gradually adding the sugar until stiff and pale.

Pour the warm milk and vegetable oil into the whipped eggs, mixing briefly on low speed.

In 2-3 batches, fold in the flour mixture, combining on low speed.

Bake the sponge cake at 300°F (150°C) for about 45 minutes and let it cool completely.

For the frosting, beat the softened butter until fluffy, add the condensed milk and nut butter, and whip until smooth.

Pulse the cooled sponge cake in a food processor into fine crumbs, gradually incorporating the cream to form a pliable dough.