Preheat oven to 350. Shred apples on box grater. To wring out excess moisture, place shreds on a dish towel and squeeze.
In a medium bowl, combine all dry ingredients (oat flour through brown sugar).
In a large bowl, combine sweetpotatoes, eggs, ACV, vanilla and coconut oil.
Pour dry ingredients into wet and stir until combined and moistened. Lastly, fold in the shredded apples to the mixture.
To make crumble, combine oat flour, oats, brown sugar, coconut oil and cinnamon in a medium bowl. Mix with a fork until coarsely crumbled.
Pour batter into muffin pan, carefully topping each muffin with crumble topping.
Bake for 20-23 minutes, or until toothpick comes out clean.