Preheat your oven to 350°F (175°C) and lightly grease an 8-inch round cake pan with oil or vegan butter.

In a small bowl, combine the almond milk and apple cider vinegar, stirring gently and letting it sit for about 5 minutes to curdle into vegan buttermilk.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt until there are no lumps remaining.

Pour the curdled milk mixture, vegetable oil, and vanilla extract into the dry ingredients.

Whisk the batter until partially combined, then slowly pour in the hot coffee (if using) or warm water while whisking until the batter is smooth and glossy.

Pour the batter into the prepared cake pan and smooth the top with a spatula to ensure an even rise.

Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs attached.

Remove the cake from the oven and let it cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

Once fully cooled, frost with your favorite vegan buttercream or dust with powdered sugar before serving.