Preheat oven to 350 degrees. Spray an 8" X 8" baking pan with nonstick spray.
In a large microwave-safe bowl, microwave butter for 45 seconds, or until melted. Add brown sugar, and whisk until uniform. Add applesauce, egg whites/substitute, and vanilla extract, and whisk until uniform.
In a medium bowl, combine all remaining ingredients except chocolate chips. Mix well. Add mixture to the large bowl, and stir until uniform. Gently stir in chocolate chips.
Pour mixture into the baking pan, and smooth out the top. Bake until a toothpick inserted into the center comes out clean, 26 - 28 minutes.