In a large bowl, sift flours, baking powder, and salt.

In the bowl of a mixer, beat the egg, yolks and sugar at a high speed for several minutes and until fluffy.

Add in the softened butter in pieces and a few at a time while mixing. Continue mixing after the all the butter is at for an additional 2 minutes.

Add the dry ingredients to the set and mix until just combined. Avoid over mixing to avoid dense biscuits and to meet edges of biscuits crispy and somewhat firm like shortbread cookies. The center of the Bretons will appear fluffy and thicker like biscuits.

Saran Wrap the dough out shaping it into a circular disc. Refrigerate for at least 30 minutes.

On a floured surface, roll out the dough and using a large cookie cutter, cut out 6 relatively large biscuits.

Place on nonstick or parchment lined sheet pan. Refrigerate for an additional 30 minutes.

Score the biscuits with a paring knife to create a diamond pattern. First, vertically, then at an oblique angle the opposite side, horizontally.

Preheat oven to 350 degrees. Bake biscuits for 18 minutes or until golden brown.