Ingredients:
1 1/2 cups unsalted butter
2 cups brown sugar, packed
2 teaspoons vanilla
5 eggs
1 teaspoon baking soda
3 1/4 cups flour
2 cups semi-sweet chocolate chips
1/2 cup cocoa powder
1 cup walnuts (optional)
Directions:
Preheat the oven to 400 F.
Line a 10 x 15 jelly roll pan with foil, and coat with non-stick cooking spray.
Using a large saucepan over medium-high heat, melt the butter. Remove from heat.
Stir in the sugar, vanilla, and 3 of the eggs until smooth.
Add the baking soda in pinches.
Mix in the flour and stir until smooth.
Pour half of the batter into the pan and spread in a thin layer.
Press the chocolate chips into the batter.
Beat the remaining eggs and cocoa into the batter until smooth. Mix in the walnuts.
Pour into the pan on top of the first layer and spread evenly.
Bake on the lowest rack for 18 minutes, until the top is dry but the interior is not yet firm.
Store for up to one week, wrapped in plastic.
Servings: 36
Time preparation: 35 min.
Time total: 53 min.