Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large bowl, combine egg with Greek yogurt and granulated sweetener.
Using a whisk or fork, mix until smoothly combined.
Gradually add in the powdered peanut butter, stirring until you get a smooth cookie dough.
Scoop out about a tablespoon of dough and roll it into a ball. Place the balls on the prepared baking sheet and flatten with a fork to create a crisscross pattern.
Bake powdered peanut butter cookies in hot oven for 7 to 9 minutes. The cookies should be golden brown on the edges and slightly soft to the touch. Do not overbake, they will firm up as they cool.
Let cool on the baking sheet for at least 10 minutes before serving.