Brush with the egg yolk mixture and place on the prepared baking sheet.

Press a chocolate half over each, rewrap and freeze on a prepared baking sheet for at least 6 hours or overnight.

Quickly dip each ball into the mixture and place on the prepared baking sheet.

Working quickly, lay the potato slices out next to one another, but not touching, on the prepared baking sheet.

Place them on the prepared baking sheet and set aside for 30 minutes to rise.

Squeeze it out onto the prepared sheet into mounds a little larger than walnuts, about 2 inches apart.

Place, seam side down, on the prepared baking sheet.

Roll each into a 10-inch circle and place on the prepared baking sheets.

Place the shell onto the prepared baking sheet.

Transfer half of the cookies to the second prepared baking sheet, spacing evenly.