Preheat the oven into 180 degrees.
Put together the dry ingredients (flour, cocoa, baking powder, soda, vanilla powder, sugar and salt) in a large bowl. Whisk to mix and aerate the ingredients. Put aside and prepare the wet ingredients. Add the wet ingredients (water, orange juice, chocolate, oil, almond milk and vinegar) in a bowl and mix well.
Add the wet ingredients into the dry ones. Mix well until it's creamy. Please note that for the vegan cakes it's important to mix very fast in order to develop gluten.
Put parchment paper in a pan, spread oil and sprinkle some flour. Add the cake mixture immediately, tap it on the counter to release the air bubbles and put in the oven on the middle rack.
Bake for 30-45 minutes, test with a clean knife and if it's ready, remove from the oven. (If the knife comes out clean your cake it's ready).
Let it cool for 5 minutes and then run a thin knife around the cake to release the cake. Place a big plate over it and turn upside down. Remove the paper, flip again and let it cool completely. When it's ready to wrap it very well with a clean film to keep it moist and place it in the fridge for 30 minutes.