Ingredients
Method
- Put the room-temperature butter, egg, cornstarch, a pinch of salt and vanilla, the icing sugar, cocoa and slaked baking soda into the bowl of a food processor. Mix with the paddle attachment (or by hand).
- Add the sifted flour and mix again - the dough is ready.
- Pinch off pieces of dough, 7-8 g each, and roll them into balls. Shape all the balls before you start baking.
- Bake the cookie halves in the walnut cookie mold - mine take 4-5 minutes per batch.
- Trim the excess dough from the baked halves and crush the trimmings into crumbs for coating.
- Fill the halves with dulce de leche, press them together in pairs and roll the cookies in the crumbs. Enjoy!

Notes
Don't throw away the trimmings from the shells - crushed into crumbs, they make the coating for the finished cookies.
