Preheat oven to 350°F.
Line a 9 by 5 inch loaf pan with parchment paper and spray with cooking spray.
Using a blender or food processor, process the oats into a flour consistency.
Combine oat flour, wheat flour, salt, baking soda, baking powder, and cinnamon in a medium bowl.
In a large bowl, combine eggs, honey, oil, and vanilla.
Add sugar to the egg mixture. Beat with a spoon or electric mixer until well blended.
Stir in apples, mixing to combine well.
Add flour mixture. Stir just until combined.
Stir in walnuts being careful not to mash.
Pour batter into loaf pan. Sprinkle with crumble topping.
Bake for 1 hour, until a wooden pick inserted in the center comes out clean.
Cool for about 10 minutes. Remove from pan and continue cooling on a wire rack.