Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners or grease it lightly with cooking spray.
In a large mixing bowl, combine whole wheat flour, rolled oats, dried cranberries, baking powder, baking soda, salt, and ground cinnamon. Mix well to combine.
In another bowl, whisk together honey (or maple syrup), the egg, Greek yogurt, fresh orange juice, orange zest, and applesauce until thoroughly mixed.
Gradually pour the wet ingredients into the dry ingredients, stirring gently until just combined. Avoid overmixing; it’s okay if there are some small lumps.
If using, fold in the chopped walnuts or almonds for extra crunch.
Divide the muffin batter evenly into the prepared muffin tin, filling each cup about ¾ full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Once baked, remove from the oven and let the muffins cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
Notes
Serve warm with powdered sugar and fresh orange slices. Store leftovers in an airtight container for up to a week.