1.
Combine flours, brown sugar, baking powder, baking soda, and salt in a bowl. In a separate bowl, beat egg with egg whites, buttermilk, and vanilla.
2.
Pour the egg mixture into the flour mixture and stir to incorporate. Let the batter rest for 10 minutes.
3.
Preheat a griddle pan over medium heat and coat with nonstick cooking spray.
4.
Working in batches, cook the batter 1/4 cup per pancake on the hot griddle. Each batch will take 3 to 5 minutes, flipping midway through cooking time to brown both sides. Serve.