Preheat the oven to 350°F (180°C).
Lightly grease a 9x5-inch (23x13 cm) loaf pan and line with parchment paper.
In a medium bowl combine oat flour, all-purpose flour, salt, baking powder, baking soda, cinnamon and nutmeg.
In a large bowl, using a whisk or an electric hand mixer, cream together the eggs with honey/maple syrup, butter and oil.
Add buttermilk and vanilla extract and mix until well incorporated.
Gently incorporate the flour mixture. Set aside.
Peel and core the apples. Cut into small pieces.
Incorporate the apples into the batter.
Pour the apple batter into the prepared loaf pan.
Top with chopped walnuts.
Bake for about 50-60 minutes until golden brown and a toothpick inserted into the center comes out clean. If the bread browns too fast, cover with aluminum foil and continue baking.
Let the bread cool completely before slicing. Enjoy!