Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a large mixing bowl, sift together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Add the eggs, milk, oil, and vanilla extract to the dry ingredients. Mix until well combined.
Gradually add the boiling water, mixing until the batter is smooth and thin.
Divide the batter evenly between the prepared pans. Bake for 25 minutes or until a toothpick inserted in the center comes out clean.
Cool the cakes in the pans for 10 minutes, then transfer to a wire rack to cool completely.