Preheat the oven to 350°F (175°C) and grease and line two 6-inch (15 cm) round cake pans with baking paper.
In a bowl, combine milk, apple cider vinegar (or lemon juice), and yogurt to make homemade buttermilk.
Add cane sugar, light brown sugar, vanilla extract, and vegetable oil. Whisk until the mixture is combined and the sugar has dissolved.
Sift in all-purpose flour, cocoa powder, baking soda, baking powder, and salt. Mix to combine.
Gradually add boiling water or brewed coffee and mix until the batter is smooth.
Divide the batter evenly between the two cake pans
Bake for 30-35 minutes, or until a toothpick inserted comes out clean.
Allow the cakes to cool completely on a wire rack. Once cooled, use a serrated knife to slice each cake into two layers or wrap each cake layer in plastic wrap to cut on the following day.