• All ingredients ready? Let's begin!
  
• Preheat the oven to 350F. Prep two round 9-inch cake pans by greasing them with butter. Sprinkle flour on the inside and tap it around until it’s stuck on the butter all over the surface of the pans. Discard any excess flour.
  

To make the cake:

• In a small bowl, add the soy milk and vinegar. Mix and set it aside.
  
• In a large mixing bowl, combine the flour, both sugars, cocoa powder, baking powder, baking soda, and salt. Whisk to mix well.
  
• Melt the butter and add it to a new bowl along with the applesauce, vanilla, and the vinegar-soy milk, which should have curdled. Mix well to combine.
  
• Add the wet ingredients to the dry ingredients and mix well. It is best to use a spatula or paddle attachment on a stand mixer. Keep mixing until well incorporated and there are no clumps.
  
• Evenly divide the batter into the previously prepared cake tins and use a spatula to smooth over the tops.
  
• Put in the oven and cook for about 35 minutes. When you can stick a toothpick or fork into the center and it comes out clean, then the cakes are done.
  
• Remove from the oven and let cool in the pans for 10 minutes.
  
• Use a butter knife around the edges of the pans to loosen the cake from the sides, then turn them upside down onto a cooling rack.
• Allow to cool completely before decorating.

For the frosting:

• Add all the ingredients except the soy milk to the bowl of a stand mixer. Alternatively, you can use an electric hand mixer, or a spoon (that will take longer).
  
• Beat the frosting ingredients together until smooth and creamy. This should take around 5 minutes.
  
• If the frosting is too thick, slowly add some soy milk bit by bit until it reaches the desired consistency. If the frosting is too thin, add more powdered sugar.
• Continue mixing until it achieves the right consistency. It should be thick and stuff enough to hold its shape but wet enough to spread smoothly and evenly.

To assemble:

• Once the cakes are cool, place one on a plate.
  
• Spoon a generous amount of frosting on top and spread roughly across.
  
• Place the second cake on top and spoon the rest of the frosting on top. Bring some frosting down to cover the sides then use an offset spatula to smooth all the surfaces.
  
• Carefully cut into pieces and serve.