In a food processor, combine the confectioner's sugar, egg yolk and butter and mix for a few seconds until creamy and smooth.
Continue by adding the flour, salt, cardamom, and rose water and mix for about 30 seconds or until you have a smooth dough.
Remove from the food processor and place in a bowl. Cover and refrigerate for about 30 minutes. The dough can remain refrigerated overnight.
Preheat the oven to 300 degrees F and line a baking sheet with parchment paper.
You can roll out the dough (1/2 inch thick) on a lightly floured surface and use a very small (1 inch) round cookie cutter to cut out the cookies. OR using a tablespoon measure, pull out a small amount of dough and using your hands turn the dough into a small round ball and place on the baking sheet.
Keep the cookies about an inch apart to make sure they don't bake into one another. The number of cookies will depend on the size of the cookies you created.
Press each cookie down to make sure they are flat and using a fork make indentations on the cookies (much like traditional peanut butter cookies).
Sprinkle half of the cookies with poppy seeds and the other half with pistachios and rose petals.
Bake in the oven for up to 15 minutes, depending on the size of the cookies.
Caution: These cookies are quite brittle and crumbly when they come out of the oven. Remove from the oven, leave on the cookie sheet until completely cooled.
Once cooled, remove from the baking pan and keep them in an airtight container and refrigerate for freshness.