Preheat the oven to 170℃ fan or 180℃ without fan, line a 9 inch round tin with baking paper and brush with oil, set aside.
In a blender add the leftover apple peels, chopped apples, eggs, sugar, vanilla, oil and blend until smooth, it should look like a smoothie.
In a large mixing bowl add the flour, baking powder, baking soda, salt, cinnamon and stir well. Pour over the wet apple mixture and whisk until combined.
Pour the batter into the prepared tin and top with cashew nuts, Demerara sugar and bake for 40-45 minutes or until a tooth pick inserted into the center comes out clean.
Top with powdered sugar once cooled and slice.