Preheat the oven to 350F and prep two 9″ cake pans with nonstick spray or vegan butter and parchment paper.
Combine dairy free milk, apple cider vinegar, and vanilla extract to make vegan buttermilk. Set aside.
Use a large bowl and hand whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Next add oil and vegan buttermilk (vinegar, vanilla and dairy free milk mixture). Mix with a spatula until just combined.
Pour in boiling hot water into the batter and carefully stir to combine. Batter will be loose and thin but this is 100% supposed to be this way.
Evenly split up the cake batter into the prepared pans and bake them together for about 33 - 37 minutes (start checking at 30 minutes) or until a toothpick in the center comes out clean. Let cool for 15 minutes in the pans, then remove and let cool to room temp before frosting.
For the Frosting
In a large bowl cream together butter and cocoa powder for about 1 minute until well-combined.
Add about half of the sugar, about half the of milk and all the vanilla extract. Turn mix on low to combine, then on high to whip the frosting together for about a minute. Repeat adding the rest of the ingredients.
Now check the consistency of the frosting. If it’s too dry, add a tablespoon at a time more dairy free milk until it reaches your desired consistency. If it’s too wet and does not a shape, add a tablespoon more powered sugar at a time until it reaches the right consistency to hold its shape.