-
1
Before baking:
-
2
Center a rack in the oven and preheat the oven to 350 degrees F. Lightly butter a 13 by 9 by 2-inch pan (quarter sheet pan), then flour it, tapping out the excess flour.
-
3
To make the Congo Layer:
-
4
Sift together the flour, baking powder, and salt onto a sheet of waxed paper; set aside.
-
5
In a large bowl, stir together the butter, brown sugar, egg, egg white, and vanilla just until blended.
-
6
Stir in the flour mixture just until the batter is smooth.
-
7
Scoop the thick, sticky batter onto 8 or 9 different areas on the bottom of the prepared pan.
-
8
With an offset spatula, spread the batter to cover the pan as evenly as possible.
-
9
Sprinkle the walnuts evenly on top and gently press them into the batter.
-
10
Partially bake the layer until it is no longer shiny on top and is beginning to come away from the sides of the pan, about 20 minutes.
-
11
Transfer the pan to a wire rack to cool while you prepare the Brownie Layer.
-
12
To make the Brownie Layer:
-
13
Sift together the flour, cocoa powder, baking powder, and salt onto a sheet of waxed paper; set aside.
-
14
In a small, heavy saucepan, melt the butter and chocolate over very low heat, stirring with a silicone spatula until smooth.
-
15
Or, combine in a medium microwave-safe bowl and melt in a microwave oven at 50 percent power (medium) for 30-second bursts, stirring after each burst, until melted, 1 to 1 1/2 minutes.
-
16
Transfer to a medium bowl and let cool for 5 minutes.
-
17
Stir the sugar into the chocolate mixture until incorporated.
-
18
Add the eggs, egg yolk, and vanilla and stir until well blended.
-
19
Stir in the flour mixture just until the batter is smooth.
-
20
Scoop the thick, sticky batter onto 8 or 9 different areas of the still-warm Congo Layer.
-
21
With the offset spatula, spread the batter as evenly as possible.
-
22
Bake the brownie until the top is no longer shiny; appears set; feels firm, rather than soft; and a round wooden toothpick inserted in the center comes out with moist chocolate crumbs attached, about 25 minutes.
-
23
Transfer the pan to a wire rack and let cool completely.
-
24
The top layer will set up as it cools.
-
25
To make the Chocolate Glaze:
-
26
Place the chocolate in a medium bowl.
-
27
In a small saucepan, bring the cream just to a boil over medium-low heat.
-
28
Pour the cream over the chocolate and let it stand for 30 seconds.
-
29
Whisk together until smooth and creamy.
-
30
Set the mixture aside at room temperature just until it cools a bit and begins to thicken slightly.
-
31
Fashion a small cone out of parchment paper and half fill it with the liquid glaze.
-
32
Snip a small opening at the end of the paper cone to allow a thin flow of glaze.
-
33
Exerting light pressure on the cone, and never easing the pressure or halting the motion, pipe thin lines of chocolate in a zigzag pattern over the cooled surface of the brownie.
-
34
Set aside at room temperature until the glaze is set, 1 to 1 1/2 hours.
-
35
To serve, cut the brownie lengthwise into seven 1 3/4-inchwide strips, and then cut crosswise into seven 1 1/4-inch-wide strips, to yield forty-nine 1 3/4 by 1 1/4-inch bars.
-
36
Or, cut lengthwise into 6 strips and crosswise into 4 strips to yield twenty-four 2-inch squares.
