42 ounces unsalted butter, softened
5 cups powdered sugar
3 vanilla beans
6 egg yolks
9 ¾ cups bread flour
3 cups sugar
Egg wash, as needed
Combine butter and powdered sugar in a bowl fitted for a stand mixer. Scrape seeds from vanilla bean and add to butter mixture. With mixer running, add 1 yolk at a time until well combined. Add bread flour until dough forms.
Divide dough into 3 balls. On a floured surface, roll balls into 1-inch-thick logs. Wrap with parchment and refrigerate 4 hours or until firm. Dough can be frozen for up to a month.
To bake, brush logs with egg wash, and roll in sugar, coating evenly. Slice logs into ½-inch-thick slices. Place rounds on parchment-lined sheet pans and bake in preheated 350 F oven 10 to 15 minutes. Cool.
Yields 12 dozen cookies or 144 cookies.