"I don't think you will find a prettier version of shortbread than this. Flecked with specks of green pistachio and pink rose petals, it's easy to make yet gorgeously impressive. Dried rose petals can be found online or in specialty spice shops."
Combine flour, confectioners' sugar, and salt in a bowl. Add cubed butter and rub everything together until mixture resembles fine bread crumbs. Add egg yolk and combine until a solid ball of dough is formed. Work in pistachios and rose petals.
Roll dough into a log, approximately 1 inch in diameter and 10 inches long. Wrap in plastic wrap and chill in the fridge for 2 hours, or up to 5 days if making ahead.
Preheat the oven to 325 degrees F (165 degrees C). Line a baking sheet with parchment paper.
Remove plastic wrap from dough once it's chilled and solid. Unwrap and slice into 1/4-inch rounds and place on the prepared baking sheet.
Bake in the preheated oven until shortbread has a light golden color, about 15 minutes. Cool and store in an airtight container.