Begin by preheating your oven to 350°F (175°C). Prepare two 8-inch (20 cm) round cake pans by greasing them thoroughly and lining the bottoms with baking paper. This ensures your cakes release easily after baking and maintain their perfect shape.
In a medium bowl, combine the milk with vinegar and let the mixture rest for about 5 minutes. During this time, the milk will curdle slightly, creating a natural buttermilk substitute that adds tenderness and a subtle tang to your cake.
Next, add the cane sugar, brown sugar, vegetable oil, and vanilla extract to the curdled milk. Whisk gently until the sugars dissolve and the mixture becomes smooth and uniform. Meanwhile, in a separate bowl, sift together the all-purpose flour, cocoa powder, baking soda, baking powder, and salt to evenly distribute the dry ingredients and prevent lumps.
Slowly incorporate the dry mixture into the wet ingredients, whisking until you achieve a smooth, lump-free batter. Finally, pour in the freshly brewed coffee or boiling water and stir until fully combined. The hot liquid not only deepens the chocolate flavor but also contributes to the cake’s moist texture.
Divide the batter evenly between the prepared pans, smoothing the tops with a spatula. Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean and the surface springs back when gently pressed.
Once baked, allow the cakes to cool in their pans for 10 minutes to set, then carefully transfer them to a wire rack to cool completely. Cooling the cakes thoroughly before frosting ensures a smooth, even finish and prevents the frosting from melting.