Preheat the oven to 350°F (177°C). Line a large baking sheet with parchment paper or a silicone baking mat.
In a medium mixing bowl, whisk together the protein powder, oat flour, tapioca flour, brown sugar, salt, and baking powder. Set aside.
In a medium size mixing bowl, using a large spoon stir together the peanut butter, apple sauce, and vanilla extract.
Pour the dry ingredients into the wet and mix together until all ingredients are incorporated. The batter will seem dry at first, but keep stirring until it comes together. Depending on the type of peanut butter and protein powder that you use, you may need to add a splash of non-dairy milk. Start with a half of a tablespoon and go from there. You don't want the dough to become too sticky to roll.
Using a heaping tablespoon, roll the dough into balls and place on the prepared baking sheet. Use a fork to press the dough balls in a criss-cross pattern.
Bake for 11-12 minutes. The cookies will appear very soft and not done, but they will set as they cool. Leave them on the baking sheet to finish setting for another 10 minutes. Don't remove too early or they may fall apart.
Enjoy these healthy treats!