Prepare the Cake

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans or line them with parchment paper.
2. Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
3. Add Wet Ingredients: Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Mix well using a hand mixer or whisk until smooth.
4. Add Boiling Water: Gradually add the boiling water to the batter. The batter will be thin, but this is normal and helps make the cake moist.
5. Bake: Pour the batter evenly into the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
6. Cool the Cakes: Let the cakes cool in the pans for about 10 minutes. Then, transfer them to a wire rack to cool completely before frosting.

Optional Frosting: Chocolate Buttercream

1. Prepare the Frosting: In a medium bowl, beat the softened butter until smooth and creamy. Gradually add the powdered sugar and cocoa powder, mixing until smooth.
2. Add Milk and Vanilla: Add the milk one tablespoon at a time until you reach your desired consistency. Stir in the vanilla extract and a pinch of salt.
3. Frost the Cake: Once the cake layers are completely cool, spread a generous amount of frosting between the layers and over the top of the cake. You can also pipe decorative designs around the edges if you like.