This recipe appears in Chef Keller's latest cookbook: Ad Hoc at Home. I was fortunate enough to meet the chef at a book signing in November; he's friendly and encouraging to cooks of all skill levels. If you're intimidated by The French Laundry, check out this book. This recipe alone is worth it.
A couple of notes on the recipe: I used a glass pan and I dusted it with cocoa instead of flour to avoid any white on the outside of my brownies. (And really, why not add more cocoa?) I also had to bake them quite a bit longer than 45 minutes so have your cake tester ready. Finally, alkalized cocoa may sound unusual, but I was happy to find that the cocoa I had in my pantry from Penzey's was alkalized. So check your label. Finally, I didn't have 61% to 64% chocolate on hand so I use 3 ounces 67% and 3 ounces semi-sweet.
Now quit reading and make these brownies. (Get a glass of cold milk ready, too.)
from Ad Hoc at Home by Thomas Keller
3/4 cup all-purpose flour
1 cup alkalized cocoa powder
1 tsp. Kosher salt
3/4 pound unsalted butter, cut into 1 Tbsp pieces
3 large eggs
1 3/4 cups sugar
1/2 tsp. vanilla paste or extract
6 ounces 61% to 64% chocolate, chopped into chip-sized pieces
Powdered sugar for dusting
Preheat oven to 350F. Butter and flour a 9-inch baking pan (Chef Keller recommends silicone, but glass or metal will work fine.) Set aside.
Sift together flour, cocoa powder and salt; set aside.
Melt half the butter in a small saucepan over medium heat, stirring occasionally. Put the remaining butter in a medium bowl. Pour the melted butter over the bowl of butter and stir to melt the butter. The butter should look creamy, with small bits of unmelted butter, and be at room temperature.
In the bowl of a stand mixer fitted with the paddle, mix together the eggs and sugar on medium speed for about 3 minutes, or until thick and very pale. Mix in the vanilla. On low speed, add about 1/3 of the dry ingredients, then 1/3 of the butter, and continue alternating the remaining flour and butter. Add the chocolate and mix to combine. (The batter can be refrigerated for up to 1 week.)
Spread the batter evenly in the pan. Bake for 40-45 minutes, until a cake tester or wooden skewer poked into the center comes out with just a few moist crumbs. If the pick comes out wet, test a second time, because you may have hit a chocolate chip: then bake for a few minutes longer if necessary. Cool in the pan until the brownies are just a bit warmer than room temperature.
Run a knife around the edges if not using a silicone mold and invert onto a cutting board. Cut into 12 rectangles. Dust the top with powdered sugar just before serving.