Preheat the oven to 350 degrees F. Line a large sheet pan with parchment.
In a large bowl, mix the ground walnuts, 3 egg yolks, sugar, Advieh, baking soda and rose water until well blended. Roll the dough into teaspoon sized balls and place 2” apart on the sheet pan. Don’t skimp on the spacing, these wafers need room to expand.
In a small bowl, whisk the remaining egg yolk and water. Press a walnut piece into each cookie and brush with the egg yolk glaze.
Bake for 20 minutes, or until golden.
Allow the cookies cool on the sheet pan for about 10 minutes, then transfer to a wire rack to cool completely.