Grease and line a 8.5 x 4.5 inch (21 x 11cm) loaf pan with parchment paper. Ensure it hangs over the sides of the tin for easy removal after baking. (see note 4)
Position the oven rack in the middle of the oven, and preheat to 356° F / 180° C (160° C fan).
In a large bowl, whisk together eggs, olive oil (or vegetable oil) vanilla extract and honey (or white granulated sugar)
Add oats, all purpose (plain flour) ground cinnamon, baking powder, salt chopped apples and walnuts or pecans (if using)
Mix together until just combined, avoid over mixing. Transfer the mixture to the lined loaf pan.
Bake for 40-45 minutes until a skewer or toothpick inserted into the loaf comes out clean.
If the top of the cake is getting too dark during baking, you can tent it with foil without letting it touch the surface of the cake.
Remove from the oven and leave the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool for about 15 minutes before slicing.