Breton Biscuits

Directions

1. 1
   Sift both flours, baking powder, and salt into a large bowl; set aside.
2. 2
   In the bowl of an electric mixer fitted with the paddle attachment, beat the egg yolks and sugar on medium-high speed until doubled in volume and pale yellow, 2 to 3 minutes, scraping down the sides of the bowl as needed.
3. 3
   Add the butter in four parts, beating until completely combined after each, 1 to 2 minutes total.
4. 4
   With the mixer on low speed, add flour mixture, beating until combined.
5. 5
   Turn out the dough onto a lightly floured surface.
6. 6
   Divide in half, and flatten into disks; wrap each in plastic.
7. 7
   Refrigerate at least 30 minutes or up to 1 day.
8. 8
   Preheat the oven to 325F, with racks in the upper and lower thirds.
9. 9
   Line two large baking sheets with parchment paper; set aside.
10. 10
    Generously dust a large piece of parchment paper with flour.
11. 11
    Place one disk of dough in the center, and roll out to slightly thicker than 1/4 inch.
12. 12
    To prevent sticking while rolling, occasionally run a large offset spatula under dough, and add more flour to the top or bottom.
13. 13
    Transfer parchment and dough to a baking sheet; chill until firm, about 15 minutes.
14. 14
    Repeat with remaining disk.
15. 15
    (You can stack sheets of dough in the freezer.)
16. 16
    Remove one sheet of dough and parchment from the freezer, and transfer to a clean work surface.
17. 17
    Using a 2 1/2-inch round cookie cutter, cut out rounds and place about 1 1/2 inches apart on prepared baking sheets.
18. 18
    Gather the scraps; roll out again and cut out more rounds.
19. 19
    In a small bowl, whisk together the whole egg and 1 tablespoon water; brush over tops of rounds.
20. 20
    Let stand 5 minutes and brush again.
21. 21
    Using a paring knife, score each round in a shallow lattice pattern, making sure not to cut all the way through the dough.
22. 22
    Repeat with remaining dough.
23. 23
    Bake, rotating sheets halfway through, until cookies are amber on top and deeply golden around the edges, 18 to 22 minutes.
24. 24
    Transfer parchment and cookies to a wire rack to cool completely.
25. 25
    Cookies can be kept in an airtight container at room temperature for up to 4 days.
26. 26
    After each round of dough is brushed with egg wash, a sharp paring knife is used to score a decorative diamond pattern on the top.