Preheat the oven to 350° and spray 3, 8" round cake pans with non stick spray. Place 8" parchment paper circles in the bottom of each pan, and set them aside.
In a medium bowl, combine the plant milk and apple cider vinegar. Set it aside, giving it atleast 10 minutes to clabber.
In a separate medium bowl, sift the flour, cocoa powder, baking powder, baking soda, and salt together. Whisk lightly until combined. Set aside.
After the milk from the first step has had time to clabber, add the boiling water and instant espresso powder. Stir to combine, and set aside.
In a large bowl (or the bowl of a stand mixer), begin mixing together the vegetable oil, applesauce, sugar, and vanilla. If using an electric mixer, mix on medium speed for 3 - 5 minutes.
Next, add your dry (flour mix) and wet (milk mix) ingredients in alternating portions, beginning and ending with dry. Do not over mix. Scrape down the sides and bottom of the bowl with a rubber spatula and mix one final time to ensure the batter is consistent and mostly clump free.
Distribute the batter evenly between the three pans, (I use a scale to help), and bake on the center rack of the preheated oven for 25 - 35 minutes. Each oven varies drastically. You'll know when your cakes are done when a toothpick inserted in the center of the cake comes out clean, and the sides of the cake begin to pull away from the edges of the pan.
Once the cakes are finished baking, remove the from the oven and allow them to cool for 10 minutes before removing them from their pans. Give them cakes adaquete time to cool to room temperature before moving to the Assembly step. You may wrap each individual cake in plastic wrap and place them in the fridge or freezer to accelerate the cooling process.
Prepare the Vegan Chocolate Mousse recipe while you wait for the cakes to cool.