In a medium bowl, whisk together the flour and salt.

In a stand mixer with the paddle attachment, or using a hand mixer, cream together the butter and powdered sugar. Mix in the egg, then the vanilla extract and orange blossom water, scraping down the bowl. Finally, mix in the flour and salt.

Scrape the dough onto a large piece of plastic wrap. Place another piece of plastic wrap on top, and roll the dough into a rectangle about 1/4 inch thick. Transfer the dough (still between the pieces of parchment or plastic wrap) to a large baking pan, and refrigerate for 30 minutes.

Remove the dough from the refrigerator, take of the top piece of plastic wrap, and flip the dough onto a large piece of parchment laid out of the counter. Remove the second piece of plastic wrap, and roll the dough a bit thinner -- to between 1/8 and 1/4 inch in thickness.

Transfer the dough, now on parchment, back to the baking sheet, and place in the freezer for 10 minutes, while you preheat the oven.

Preheat the oven to 350 F.

Remove the baking sheet with the dough from the freezer, and transfer the dough, on the parchment, to the counter. Use a 1.5-inch or 2-inch fluted round cookie cutter to cut out as many cookies as you can, transferring them to a baking sheet lined with a fresh piece of parchment paper. Re-roll the dough scraps, and continue cutting out cookies, popping the dough back in the freezer for a few minutes if it gets too soft.

Place the baking sheet with all the cut-out cookies back into the freezer for 5 minutes again--this will help the cookies keep their shape when they bake.

In a small bowl, whisk together the egg white and a tiny drop of orange blossom water (if you wish).

Remove the baking sheet from the freezer. Take one of your flowers, snip the stem off as close to the petals as you can, then lightly press the flower flat on top of a cookie. (If the petals fall apart, just rearrange them on top of the cookie.) Brush some of the egg white mixture over the the flower, then sprinkle on some granulated sugar. Repeat with the remaining cookies and flowers.

Bake the cookies for 10-14 minutes, until the edges are just beginning to turn light brown. (The exact baking time will depend on your oven, and the size and thickness of your cookies).

Allow to cool on the pan for 5 minutes, then transfer to a rack to fully cool.

The cookies will keep at room temperature in an air-tight container for at least 4-5 days, and can be kept well-wrapped in the freezer for much longer.