Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans, or line them with parchment paper.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.

Add the eggs, milk, oil, and vanilla extract to the dry ingredients and mix until well combined.

Carefully pour in the boiling water, and continue mixing until the batter is smooth. The batter will be thin, but that's just right.

Divide the batter evenly between the prepared cake pans.

Bake for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for 10 minutes, then remove from pans and transfer to a wire rack to cool completely before frosting.