Preheat the oven to 350 degrees F. line (1) 8” or 9" cake pan with parchment paper. Spray with cooking spray and set aside.
In a small bowl combine soy milk and apple cider vinegar. Mix together and set aside for 5 minutes to allow the milk to curdle. Once curdled, add coconut oil, vanilla extract, and granulated sugar to soy milk mixture and whisk together.
In a large bowl whisk together cocoa powder, flour, baking soda, baking powder, and salt. Pour the wet ingredients into the dry and gently mix to combine; a few lumps are okay. Once your cake batter is well hydrated, add the warm water and whisk until the water is fully incorporated.
Pour the batter into the prepared cake pan and bake for 50-60 minutes until a toothpick inserted in the middle comes out clean. Remove from the oven and let the cake cool for at least 30 minutes before removing it from the cake pan. Let the cake continue to cool on a wire cooling rack.