Preheat oven to 350 degrees F and line muffin tin with parchment paper liners and spray with cooking spray. Set aside.
In a large mixing bowl, add eggs, applesauce, maple syrup, oil, vanilla extract, cinnamon, nutmeg, baking powder, baking soda, and salt. Whisk well to combine, making sure baking powder and soda are dissolved. Add flour and stir gently to mix. Do not over mix.
Add grated apples and walnuts, give a few stirs just until combined.
Using large ice cream scoop, fill 12 tin openings with batter. They will be very full. Bake for 23 minutes or until toothpick inserted in the middle comes out clean.
Remove from the oven, let muffins cool in the tin for 5 minutes and then transfer to a cooling rack to cool more, or enjoy warm.
Notes
Store: Store in an airtight container in a cool dry place for up to 3 – 4 days or in a fridge for up to a week.
Freeze: Bake and cool muffins completely. Arrange in a single layer in resealable plastic bag or any container with a lid. Freeze for up to 3 months.
Apples: Bets apples to use are any sweet variety like Honeycrisp, Fuji, Pink Lady or Gala apples work. You can also use one sweet apple and one tart apple like Granny Smith. Grated is better than chopped, and it's up to you if you want to peel it or not.
Other flours: You may also use whole wheat pastry flour or white whole wheat flour. I have not tested it with gluten free flour, so can't tell. You can try my almond flour blueberry muffins and replace blueberries with grated apple.
Other add-ins: Up to a 1/2 cup of chocolate chips, dried cranberries or raisins.