- Preheat oven to 350°F. Grease a 12-cup muffin tin or line with muffin liners. 
- In a large bowl, whisk together the whole wheat flour, oat flour, baking powder, baking soda, cinnamon, nutmeg, and salt. 
- In a medium bowl, whisk together the melted vegan butter or coconut oil, honey, flax eggs, and applesauce until combined. 
- Add the wet ingredients to the dry ingredients and stir until just combined. Fold in the diced apples. 
- Divide the batter evenly among the muffin cups. Bake for 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean. 
- Let the muffins cool in the tin for 5 minutes before transferring to a wire rack to cool completely.