Preheat oven to 350 degrees. Line 36 mini muffin tin holes with mini cupcake wrappers.
In a large mixing bowl, combine brownie mix, water, applesauce, and egg whites. Mix 50 times with a wooden spoon (use 50 strokes); do not under or over mix. Pour brownie mixture into prepared muffin tins, about 1 tablespoon per hole.
Bake cupcakes until a tester inserted in center of a cupake comes out clean, about 12-15 minutes. Remove from oven and cool completely; remove cupcakes from pan. Before serving, dust with powdered sugar.