Add powdered peanut butter and baking powder. Mix well.
Fold in peanuts.
Bake in an 8" round (or similarly sized) silicone pan for about 16 minutes, or until firm and a toothpick comes out clean. If not using silicone, line pan with parchment paper.
Enjoy! Store in the refrigerator.
Notes
A note about substitutions: because each type of protein powder has a distinct flavor and texture when baked, I would not try substituting different types of protein powders in this recipe. (See my Recipe Basics video for examples of what goes wrong when you use the wrong protein powder.)