Make the pistachio filling : In a medium bowl, whisk the egg. Using a spatula, mix in the pistachio flour, sugar, rose water, and butter. Refrigerate until ready to use.
Make the cookie dough: In a large bowl, add the butter, sugar, and powdered sugar. Mix with a spatula until combined. Mix in the egg, almond extract, baking soda, and salt until well-combined. Add the flour and stir until no dry spots remain.
Assemble the cookies: Using a quarter-cup ice cream scoop, portion out the cookie dough into balls and set on a plate or tray. Remove the pistachio filling from the refrigerator. Take a cookie dough ball and flatten it into a pancake. Using a two-tablespoon cookie scoop, scoop the pistachio and plop it into the center of the dough pancake. Envelope the cookie dough around the pistachio filling and roll until smooth. Repeat for all dough balls. Take the sliced rose petals and press them into the top of each dough ball. Refrigerate the cookies until oven is preheated.
Bake: Preheat oven to 350F with a rack set in the center. Add 8 dough balls to a parchment-lined half-sheet tray. Bake for 14-16 minutes, until the cookies are just turning golden at the edge. Remove from the oven and let cool for 5 minutes. Remove cookies to a plate or wire rack. Dust with the powdered raspberry. Repeat baking process with remaining cookies.
