Preheat the oven to 350 degrees F and grease two 8-inch cake pans. I also line them with parchment rounds for easy removal of the cakes later.

Measure 1 cup unsweetened soy milk and add the tablespoon of vinegar to it. Stir slightly and set aside to curdle.

In a large bowl, add the flour, sugar, cocoa powder, baking powder, baking soda and salt. Whisk well to combine.

Now add the oil, applesauce, vanilla and milk/vinegar mixture. Mix on medium speed with a hand mixer (or stand mixer with the paddle attachment) until well combined.

Lower the speed and carefully pour in the boiling water, continuing to mix into the cake batter until combined. The batter will seem very runny at this point; that is how it should be, trust me!

Divide the batter evenly between your cake pans. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. After 10 minutes of cooling in the pan, carefully invert the cakes onto a cooling rack and let cool completely.

In the bowl of a stand mixer with a paddle attachment or in a large mixing bowl with an electric hand mixer, beat the butter until smooth, about 2 minutes.

Gradually add the powdered sugar, about a cup at a time, and mix starting on low speed gradually increasing to medium, until all the powdered sugar is mixed in.

Add the vanilla and 1/4 cup of the cooled salted caramel and beat on medium speed for 3-4 minutes, until everything is well combined. Scrape the bowl as needed.

Spread the frosting evenly between the layers, on top and on the sides of the cake. Spread a thin layer of salted caramel sauce on top of the cake and use an offset spatula to push the caramel off the edges to create pretty drips.

Keep the cake in the refrigerator until ready to serve. It will keep for 4-5 days in the refrigerator, but is best served within 1-2 days. It's best to let it come to room temperature before serving.