Center rack in oven and preheat to 325 degrees F. Line a baking sheet with some parchment paper.
In a food processor add the flour, sugar, anise seeds (if desired), baking soda, and salt; pulse to blend. Drop in the pieces of cold butter; process in long pulses until mixture is grainy looking. In a small bowl combine yolks, orange flower water, and honey; add to processor in small measures, pulsing in short spurts after each addition and then until mixture turns to moist curds, scraping bottom of bowl as needed.
Transfer dough to counter; knead lightly until mixture holds together. Place between two pieces of parchment paper; roll 1/4 inch thick.
Peel top sheet of parchment off dough. Flip onto a clean sheet of parchment paper. Peel off remaining sheet of parchment. Using a 13/4-inch- diameter round cutter, cut out as many circles as you can. Transfer to a baking sheet (they won't spread much, so place close together). Use 3/4-inch-diameter round cookie cutter to remove centers. Shape scraps into a disk; roll and cut. (Gather, roll, and cut scraps once more.
Bake cookies for 18 to 20 minutes (rotate sheet from front to back after 10 minutes) or until golden and firm enough to lift. Place baking sheet on wire rack; dust cookies with a little powdered sugar or let cool to glaze.
For glaze: In a small saucepan bring 3/4 cup powdered sugar and 3 Tbsp. water to boiling. Boil at a moderate rate until candy thermometer registers 235 degrees F to 240 degrees F, or soft-ball stage (about 4 minutes). In small bowl whisk egg white 1 to 2 minutes or until soft peaks form.
Anchor bowl of egg white on a silicone potholder or dish towel; whisk egg white as you pour in hot sugar syrup in a slow, steady stream. Using a pastry brush, brush each cookie with glaze. Allow glaze to set at room temperature.