Preheat the oven to 350°F and line two 9” cake pans with parchment paper.
Mix the milk and apple cider vinegar and set aside.
Mix the dry ingredients in a large bowl: flour, cocoa powder, sugar, baking powder, baking soda, and salt.
In the same bowl, add the wet ingredients: the curdled milk we already prepared, oil, apple sauce, and vanilla extract.
Carefully add in the boiling water and instant coffee.
Pour batter into the cake pans, and bake for 30–35 minutes. Once baked, let them cool before frosting.