Start by preparing your french toast batter by adding non-dairy milk, peeled apple, cinnamon and vanilla extract into a blender. Blend until smooth, then strain into a large mixing bowl. If you are using apple cider, skip the blending and just whisk everything in a large bowl. Next, whisk in flax seeds and arrowroot flour and let mixture sit for about 5 minutes.
Meanwhile, prepare your cooked apples. In a saucepan over medium heat, add apples, sugar, cinnamon and nutmeg if using and cook down with water or oil until soft and fragrant. Cook time will vary based on the size of your apple chunks. Remove and set aside.
Next, place a slice of bread or two into the batter, flip and let sit for about a minute to soak up the moisture. Prepare another pan, or us the same one you used to cook the apples down, and add a touch of neutral oil. Place as many slices of bread into the pan as you can fit and let cook until edges start to lightly brown, about 2 minutes. Use a spatula, flip and cook the other side for another few minutes, or until golden brown. Repeat until all the bread or batter is used.
To serve, plate french toast, top with cooked apples, crushed walnuts and maple syrup if desired. You can also dust with additional cinnamon, powdered sugar or non-dairy yogurt as well.