In a mixing bowl, whisk the egg whites until foamy; gradually mix in the sugar; then mix in the cocoa powder, oil, yogurt, vanilla; mix in the salt and baking powder (making sure the baking powder doesn’t clump); add the flour (you can either stir in the chocolate chips now or sprinkle on spread batter later).
Pour batter onto the cookie sheet and spread as thinly as possible using the back of a spoon or scraper.
Bake at 325 degrees Fahrenheit on center rack for 20 minutes. Remove from oven and sprinkle crushed candy cane pieces over the cooked brownie bark (reserve about 1 tbsp). Place back in oven at 325 degrees Fahrenheit for about 1-2 minutes until the candy cane pieces are slightly melt. Remove from oven and immediately sprinkle with remaining candy cane pieces.
Let completely cool for 10-20 minutes. When cool take a pizza cutter or knife and cut into pieces – you want shards, similar to what you’d get if making peanut brittle