Preheat the oven to 350°F (180°C). Line a baking sheet with parchment paper and set aside.
In a mixing bowl, combine the peanut butter, brown sugar substitute, egg, and vanilla protein powder until a uniform dough forms.
If using, fold the chocolate chips into the dough until evenly distributed.
Shape the dough into 12 equal balls using your hands, place them on the prepared baking sheet, and press each ball down gently to form cookie shapes.
Bake for 12–14 minutes, or until the edges begin to brown.
Remove the cookies from the oven and let them cool on the baking sheet until completely cooled.