2 1/2 cups all-purpose flour
1 cup white sugar
1/2 cup unsweetened cocoa powder
1/2 teaspoon salt
1/4 cup unsalted butter
2 eggs
2 teaspoons vanilla extract
2 tablespoons brown sugar
2 tablespoons unsweetened cocoa powder
2 tablespoons unsalted butter
2 tablespoons light cream
1/2 cup chopped pecans
Preheat oven to 350 degrees F (175 degrees C).
Sift together the flour, sugar, cocoa, and salt; set aside. In a large bowl, mix egg yolk mixture, white sugar, and cocoa until smooth. Stir egg mixture into flour mixture, and stir until just moist. Blend in butter and eggs. Pour crust mixture into greased and floured 9x13 inch baking pan.
Tuck cardigans inside bars, sealing well. Spread 1/2 of the egg whites inside of every crease. Spread 1/2 teaspoon of cream over each crease. Make big cuts in, pressing each cut to ensure even cooking. Of course, you want the edges to be long enough that they'll stick together.
Bake for 30 seconds in the preheated oven. Cool completely, then cut bars with biscuit form and arrange in shallow baking pan. Let cool completely, about 8 minutes before cutting into squares.