Step 1: Prepare the Dough

1. In a large mixing bowl, cream together the softened butter and powdered sugar until light and fluffy.
2. Add the vanilla extract and rosewater, mixing until well combined.
3. Gradually add the flour and salt, mixing until just combined.
4. Fold in the finely chopped pistachios until evenly distributed throughout the dough.

Step 2: Shape the Cookies

1. Divide the dough into two equal portions. Roll each portion into a log about 1.5 inches in diameter.
2. Wrap each log in plastic wrap and refrigerate for at least 1 hour, or until firm.

Step 3: Preheat the Oven

1. Preheat your oven to 350°F (175°C).
2. Line a baking sheet with parchment paper.

Step 4: Slice and Bake

1. Once the dough is firm, remove it from the refrigerator and unwrap the logs.
2. Slice the logs into 1/4-inch thick rounds and place them on the prepared baking sheet, spacing them about 1 inch apart.
3. If desired, gently press a few chopped pistachios or edible rose petals onto the top of each cookie for decoration.

Step 5: Bake

1. Bake in the preheated oven for 12-15 minutes, or until the edges are lightly golden.
2. Remove from the oven and allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.