Preheat your oven to 350°F (175°C). Grease a 9x13-inch rectangle pan with oil and line it with an overhang of baking paper for easy removal and the cake doesn’t stick. Alternatively you can also bake this in two 8x8-inch square pans.
Grate the red apples using a box grater. You’ll need about 3-4 medium apples. Once grated, squeeze out the extra juice so the cake doesn’t turn soggy and stodgy.
In a large mixing bowl, whisk together milk, oil, vanilla extract, light brown sugar, and cane sugar. Keep whisking until the sugars are fully dissolved and the mixture looks smooth.
In another bowl, combine the dry ingredients - flour, baking powder, baking soda, cinnamon, and salt.
Slowly add the dry ingredients to the wet mixture and mix with a whisk until just combined. Make sure there are no dry flour pockets, but don’t over mix.
Gently fold in the grated apples with a spatula. This will give the cake natural sweetness, moisture, and that classic apple flavor.
Pour the batter into your prepared pan and bake for about 25–30 minutes. The cake is ready when the top feels firm to the touch and a toothpick inserted comes out clean.
Let the cake cool in the pan for a few minutes, then transfer it to a wire rack to cool completely. Peel off the baking paper and allow it to cool further before adding frosting.