Edible flowers: we recommend pansy viola, nasturtium, dianthus, and borage blossom
Preheat the oven to 375° F. Line a rimmed baking sheet with parchment paper and set aside.
In a large bowl, whisk together the flour, sugar and salt. Create a well in the center of the dry ingredients and add the butter, mix with a spoon until combined. Scatter the pistachio pieces over the dough and knead with hands until the dough comes together and is smooth. Wrap tightly with plastic wrap and chill for at least 10 minutes.
Remove dough from refrigerator and place between two sheets of parchment paper. Roll dough to about 1/4 inch thickness and cut out cookies with a 1 1/2 inch round cutter, and place them on the lined baking sheet. Artfully place the flowers or individual petals on the cookies and press gently into the dough.
Bake on the center rack of the oven for 10-12 minutes, until the edges turn slightly golden. Remove from the oven and sprinkle immediately with sugar, then allow to cool.
Note: Cookies may be kept at room temperature in an airtight container for 3 days. If your gluten-free flour blend doesn't contain baking binder, add 1 tsp to the flour before mixing.