Preheat the oven to 350°F (180°C). Grease and line two8-inch cake pans with parchment paper.
In a large bowl, whisk together the milk and lemon juice.Add the sugar, oil, and vanilla extract, and whisk until combined.
In a separate bowl, sift together the flour, cornstarch, baking powder, baking soda, and salt. Add the dry ingredients to the wet ingredients and mix until just combined. Do not over mix.
Divide the batter evenly between the prepared pans and tap them gently on the counter to release any air bubbles.
Bake for 22–25 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.