In a small bowl, stir together non-dairy milk and apple cider vinegar. Let the mixture sit and curdle.
In a medium bowl, sift together flour, cocoa powder, salt, baking soda, and baking powder. Set it aside.
In a large bowl, combine the eggs, granulated sugar, brown sugar, oil, non-dairy milk mixture, and vanilla extract.
Add the flour mixture into the wet ingredients and mix until just combined. Pour in the hot coffee and stir again until a smooth mixture forms. Cover the bowl and let the batter rest for 30 minutes.
While the batter rests, preheat the oven to 340°F (170°C) and grease and line three 6-inch round pans (or two 8-inch round pans) with parchment paper.
Evenly pour the batter into the cake pans and bake for 32-35 minutes. Let the cakes cool in the pan for 10 minutes before taking them out onto a cooling rack to let them cool completely.
Once cooled, wrap each layer with plastic and put it in the fridge or freezer for an hour.