1. In a bowl, with an electric mixer on high speed, beat butter and granulated sugar until smooth. Add hard-cooked egg yolks, uncooked egg yolk, uncooked whole egg, and salt; beat on medium speed until blended. Stir in flour.
2. Shape dough into 1-inch balls; cover with plastic wrap. On a lightly floured board, roll each ball under your palm into a 6-inch-long rope. On a 12- by 15-inch baking sheet (you'll need three total), twist each rope into a figure eight and press ends lightly together; space twists about 1 inch apart. Beat remaining egg white to blend; lightly brush over twists. Sprinkle with pearl sugar.
3. Bake in a 350° oven until twists are golden brown, about 18 to 20 minutes; switch pan positions halfway through baking. With a wide spatula, transfer twists to racks to cool.
Note: Nutritional analysis is per twist.