Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or coat with cooking spray.
Combine the powdered peanut butter, sugar replacement, chopped oats, baking powder, and salt in a bowl using a hand mixer.
Add in the mashed banana, egg, and vanilla and beat until well combined.
Slightly overfilling a #50 scoop or a tablespoon, either sprayed with cooking spray, scoop out the dough into 12 portions and place them equally distanced from each other on the prepared baking sheet. Place the sheet in the freezer for 10-15 minutes to firm up the dough.
Remove the pan from the freezer and, with damp hands, flatten each dough ball. If desired for a peanut butter cookie look, spritz each cookie lightly with cooking spray and use a fork to create a crisscross pattern on each cookie.
Bake 12-15 minutes until set. Cool at least 10 minutes before serving.
