Preheat oven to 400 degrees. In a medium bowl, stir together the applesauce, egg substitute, and skim milk until well mixed. Stire in the baking mix and 3/4 cup Splenda, mixing well. Gently fold in the blueberries and blackberries. Mix just enough to get them evenly scattered throughout the batter. Line 12 regular size muffin cups with cupcake liners and coat the liners with nonfat cooking spray. Fill each cup 3/4 full with batter. Bake for 18-20 minutes or until a toothpick inserted in the center of a muffin comes out clean. Let cool a few minutes. Coat the top of the muffins with nonfat cooking spray and lightly sprinkle with the remaining 1 Tbsp. Splenda. If desired, you can also sprinkle the tops of the muffins lightly with ground cinnamon or cinnamon sugar.