Preheat the oven to 350°F.
In a large bowl, use a hand mixer or stand mixer to beat the sugar, canola oil, eggs and vanilla extract until well blended.
In a separate bowl, whisk together the all-purpose flour, baking powder, salt, cinnamon and baking soda.
Gradually beat the flour mixture into the sugar mixture until blended.
Use a rubber spatula to fold in the chopped apples and walnuts until they’re evenly dispersed.
Grease a 13x9-inch baking dish and pour the batter into the pan.
Bake the cake until a toothpick inserted in the center comes out clean, 35 to 45 minutes.
Cool the cake on a wire rack at room temperature, and serve your apple cake slices with the whipped topping.
