Here is the recipe you requested. Now remember, it is a secret recipe. Don't tell anyone!
16 tablespoons butter
8 ounces bittersweet or semisweet chocolate, cut into 1/4-inch pieces
4 large eggs
1/2 teaspoon salt
1 cup sugar
1 cup firmly packed dark brown sugar
2 teaspoons vanilla extract
1 cup all-purpose flour
2 cups chopped nuts (optional)
Preheat oven to 350 degrees. Bring a saucepan of water to a boil. Turn off heat. Set a heatproof bowl over water, and put butter and chocolate in bowl. Melt, stirring occasionally. In a separate bowl, whisk eggs. Add salt, sugars, and vanilla. Stir in chocolate and butter mixture. Fold in flour and nuts. Pour batter into a 9x13 pan that has been buttered/sprayed. (The recipe also suggests lining the pan with buttered parchment or foil.) Spread batter evenly in pan. Bake for 40 to 45 minutes.
The top will form a shiny crust and the batter will be moderately firm. And you have to spend the money on the good chocolate, or it's just not the same.