Combine the water and yeast in a small bowl. Let stand for 10 minutes, then stir until the yeast is completely dissolved. Set aside.
together the flours, sugar
, and salt into the bowl of a stand mixer
fitted with the dough hook. Add the eggs and beat for 1 minute at low speed, scraping down the sides of the bowl with a rubber spatula
as needed. Slowly add the dissolved yeast and continue beating at low speed for 5 minutes. Stop the machine, scrape any dough off the hook, and beat for another 5 minutes.
Add about one-quarter of the butter cubes at a time, beating for about 1 minute after each addition. Once all the butter has been added, beat for 10 minutes more.
Place the dough in a large floured bowl and cover with plastic wrap. Set aside in a warm place until doubled in size, about 3 hours.
Turn the dough out onto a generously floured work surface and gently work the air bubbles out by folding the dough over several times while lightly pressing down on it.
Return the dough to the bowl, cover with plastic wrap
, and refrigerate overnight.
The dough is now ready to shape or use in another recipe. Generously butter two 8 1/2 by 4 1/2-inch loaf pans. Turn the dough out onto a floured work surface. With floured hands, divide the dough
in half and shape it into two rectangles that fit in the loaf pans. Place the dough in the pans.
Let the dough rise uncovered in a warm place until it is about 1/2-inch above the top of the pans, about 3 hours.
Preheat the oven to 350 degrees F.
Bake the brioche in the center of the oven until it is well browned on top and sounds hollow when tapped on the bottom, 35 to 40 minutes. Remove the brioche from the oven and immediately turn out onto a wire rack.
If serving immediately, let the breads cool for 10 minutes, then slice. If serving within a few hours, wrap the hot bread in aluminum foil and set aside at room temperature until ready to use. To freeze, wrap the hot bread in foil and promptly freeze. The bread can be kept frozen for up to 1 month; when ready to use, reheat (without thawing and still wrapped in the foil) in a 250 degree F oven until heated through, 20 to 25 minutes.
If using the brioche for croutons, let sit at room temperature uncovered to dry for a day.
Yield: 2 loaves