1Preheat oven to 350°F (175°C) and prepare a muffin tin by lining it with muffin cups or lightly greasing it.
2In a large bowl, combine oat flour, chocolate protein powder, cocoa powder, baking powder, baking soda, and salt. Stir until well mixed.
3In another bowl, whisk together eggs, unsweetened applesauce, Greek yogurt, honey/maple syrup, and vanilla extract until smooth. Add milk and mix well.
4Pour wet ingredients into dry ingredients. Stir until just combined, being careful not to overmix. Gently fold in chocolate chips, if using.
5Divide batter evenly among muffin cups, filling each about 3/4 full. Bake for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs.
6Allow muffins to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.