Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1      cup           all purpose flour
   1 1/2  teaspoons     baking powder
     1/2  teaspoon      salt
     1/2  pound         unsalted butter -- melted
   1 1/2  cups          tightly packed dark brown sugar
   2      large         eggs
   1      teaspoon      pure vanilla extract
   4      ounces        semi-sweet chocolate chopped into -- 1/4"-chunks
   4      ounces        white chocolate chopped into -- 1/4"-chunks

Preparation:

Preheat the oven to 350 degrees F. In a sifter combine the flour, baking powder, and slat. Sift onto a larg piece of wax paper and set aside until needed. Place the butyter and brown sugar in a 7 quart bowl and whisk to combine. Add the eggs and vanilla extract and whisk until smooth. Add the sifted dry ingredients and use a rubber spatula to incorporate. Add the semisweet and white chocolate chunks and stir to incorporate. Pour the batter into the non stick baking pan and bake on the center rack of the preheated oven for 25 min until set in the center. Remove the pan from the oven and allow to cool at room temperature for 1 hour before cutting. Cut brownies into 24 2 inch squares. Serve immediately or store in a tightly sealed plastic container