Preheat the oven to 350°F (175°C) and line a baking sheet with silicone mat or parchment paper.

In a large mixing bowl, whisk together the Greek yogurt, egg, and erythritol until the mixture is smooth.

Sift the protein powder and baking powder into the wet mixture, then add the oats and cinnamon.

Stir the ingredients until a thick, uniform dough is formed.

Gently fold in the sugar-free chocolate chips using a spatula.

Using a cookie scoop or tablespoon, drop 12 equal portions of dough onto the prepared baking sheet.

Slightly flatten the tops of the cookies with a damp spoon as they will not spread much during baking.

Bake for 10 to 12 minutes until the edges are golden and the centers are set.

Cool on the baking sheet for 5 minutes to allow the protein structure to firm up before transferring to a wire rack.