Makes about 30 cookies. Adapted from Smitten Kitchen.
2 sticks (8 ounces) salted butter, cold
1 teaspoon vanilla extract
3 cups all-purpose flour
¾ cup granulated sugar
¼ cup powdered sugar
2 teaspoons baking powder
2 teaspoons Fleur Spice
1 batch 'sweetheart' glaze (recipe follows)
1 tablespoon rose petals, crushed (optional)
Cut the butter into small cubes (about ¼-inch). Whisk the egg and vanilla extract together in a small bowl. Cut two cookie-sheet sized pieces of baking parchment. Set these three things aside.
Put the flour, sugars, baking powder, and Fleur Spice into the bowl of a food processor fitted with the metal chopping blade. Cover and pulse a few times to fluff and thoroughly mix the dry ingredients.
Add the butter to the bowl, cover, and process until the mixture looks like fine sand. With the processor running drizzle the egg mixture through the feeder tube in the lid. Stop the machine when the dough starts to clump a little (it will not have come together in a ball).
Transfer the mixture to a mixing bowl and press it firmly-but-gently (don't knead) to bring it together into a clump of dough. Place the dough on one of the sheets of parchment paper and pat it into a rectangular block, about 7"x 12".
Put the remaining piece of parchment over the dough. Roll with a pin until the dough is about ¼-inch thick. Remove the top paper; use the bottom sheet to transfer the dough to a cookie sheet. Chill the dough in the freezer for 15 minutes (or an hour in the fridge).
While the dough chills, line another cookie sheet with baking parchment and set aside. Preheat the oven to 350° F.
Use the parchment to lift the sheet of dough from the cookie sheet to a work surface (leave the dough on the parchment). Cut it using cookie cutters or a cutting wheel. Place the cookies about ¾-inch apart on the lined baking sheet. Bake until the bottoms are barely golden, about 15–18 minutes. Cool the cookies on the baking sheet for 10 minutes before transferring them to a rack to cool completely.
Decorate the cookies by dipping the tops into the glaze (recipe below) or drizzling glaze over them. While the glaze is still wet, sprinkle a pinch of crushed rose petals over each cookie. Allow about an hour for the glaze to set, then stow the cookies in an airtight container, where they will keep for three or four days at room temperature or freeze them for longer storage.
Mix 2 teaspoons Fleur Spice with the juice of a lemon. Set aside to infuse for 20 minutes. Pour the lemon juice through a fine mesh strainer, retaining the red juice and discarding the spice solids. Separately, whisk an egg white until it's frothy.
Put 1½ cups powdered sugar into a bowl. Add 3 tablespoons of the Fleur-infused lemon juice, 2 tablespoons water, 2 teaspoons of the egg white, and a tiny pinch of salt. Whisk, slowly to combine, then vigorously to smooth.
Note: You can make these cookies using a mixer, but you'll change the order of operation. First, mix the flour with the baking powder. Separately, cream the butter, sugars, and the Fleur Spice. Beat in the egg and vanilla. Finally, mix in the flour until it's just combined with the butter-egg mixture.