2cupschopped apples, peeled or not (2 to 3 apples, I used Pink Lady's)
Ideal slow cooker size: 6-Quart to 7-Quart.
Grease and flour a bread pan or baking dish that fits in your slow cooker. Place a trivet or metal mason jar rings in the bottom of your slow cooker to support the pan.
In a medium bowl, whisk together the sugar, oil, egg and vanilla until creamy and well blended.
In a separate bowl, whisk together the flour, baking soda, baking powder, cinnamon and salt.
Stir the flour mixture into the sugar mixture until well combined. Stir in the apples and walnuts. (It will seem like too little batter for so many apples, but it's not.)
Scrape the batter evenly into the prepared pan. Cover the pan with foil. Set into the cooker.
Cover the slow cooker with the slow cooker lid. Bake on HIGH for 2 to 3 hours, or until a toothpick inserted into the center of the cake comes out clean. Begin checking after the slow cooker apple cake has been cooking 2 hours. If it isn't done, cover and continue cooking for 15 to 30 more minutes and then check it again.
When the cake is done, carefully lift the hot baking pan out of the slow cooker and set it on a wire rack to cool for at least 15 to 20 minutes before serving.