Preheat oven to 375°F (190°C). Grease a muffin tin.

In a large bowl, combine oats, flour, protein powder, baking powder, baking soda, and salt.

In a separate bowl, whisk together applesauce, milk, and egg.

Combine wet ingredients with dry ingredients, mixing until just combined.

Stir in nuts and dried fruit (if using).

Divide batter evenly among muffin cups.

Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.

Let cool in the muffin tin for a few minutes before transferring to a wire rack to cool completely.

Store in an airtight container in the refrigerator for up to 3 days or freeze for longer storage.