Preheat oven to 350°F and line 2 baking sheets with parchment paper (or a silicone baking sheet).
Add powdered sugar, cocoa, and salt to a mixing bowl and whisk to combine. Add the egg whites and egg. Whisk a little bit at a time - this will take a few minutes - until fully incorporated and wet. It will be quite thick.
Add the peanut butter and chocolate chips and just slightly mix. Leave some swirls so the peanut butter will be visible when baked. Spoon 1 Tablespoon of batter, 2" apart to form about 27 cookies. Do not flatten the batter; it will spread as it bakes.
Bake 7 minutes. Rotate the baking tray and bake another 7 minutes and remove promptly. Allow to cool for 5 minutes before removing from the tray.
Drop Cookies - What should the batter look like?
These are drop cookies - meaning the batter will be wet and sticky.
What Do These Cookies Look Like When Baked Properly?
The cookies may appear under-baked right out of the oven. That's ok. They continue to cook a bit after you remove them. They should not taste burned at all. The inside should be soft and there will be gooey areas where the chocolate chips/peanut butter are concentrated.