Preheat oven to 350°F (175°C). Grease three 8-inch (20 cm) round cake pans and line them with parchment paper so the cakes don’t stick.
In a small bowl, combine the milk and vinegar. Let it sit for 5 minutes it will thicken slightly and look a bit curdled.
Add the water, vegetable oil, and sugar to the milk mixture. Whisk everything together with a whisk until smooth and well combined.
In another bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt. Sifting helps remove lumps and keeps the cake light and fluffy.
Slowly add the dry ingredients into the wet mixture. Mix gently with a whisk until just combined. don’t over mix or the cake may turn dense.
Divide the batter evenly among the three pans. Bake in the preheated oven for 20–22 minutes, or until a toothpick inserted in the center comes out clean.
Let the cake layers cool completely in the pans for 30 minutes, then carefully transfer them to a wire rack to cool fully. This prevents them from breaking or sticking.